High responders and low responders: factors associated with individual variation in response to standardized training

Effect of hypoxia conditioning on physical fitness in middle-aged and older adults-a systematic review and meta-analysis

Background

Hypoxic conditioning has emerged as a promising intervention for enhancing physiological adaptations. This systematic review and meta-analysis of randomized controlled trials aims to investigate the efficacy of hypoxic conditioning on physical fitness measures in aging populations.

Methods

The Embase, PubMed, Cochrane Library, and Web of Science were searched from inception to November 2024 (Prospero registration: CRD42023474570). The Cochrane Evaluation Tool and Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework were used for risk of bias assessment and evidence certainty evaluation. Mean differences (MD) and standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated using the Review Manager software. Subgroup analysis was performed to explore possible associations between the study characteristics and the effectiveness of the intervention.

Results

A total of 13 randomized controlled trials (RCTs) with 368 subjects were included in the meta-analysis. High certainty evidence found hypoxic conditioning (HC) significantly improved peak oxygen uptake (VO2peak) (SMD = 0.31, 95% CI [0.01-0.61]; P < 0.05), while very low to moderate certainty evidence shown that hypoxic conditioning (HC) have not induced greater changes on functional outcomes (SMD = -0.21, 95% CI [-0.66-0.24]; P > 0.05), muscle strength (SMD = -0.19, 95% CI [-0.63-0.26]; P > 0.05), maximal power output (SMD = 0.29, 95% CI [-0.17-0.76]; P > 0.05), VO2max (SMD = -0.39, 95% CI [-1.12-1.90]; P > 0.05), and exercise workload (MD = -10.07, 95% CI [-34.95-14.80]; P > 0.05).

Conclusion

This study suggests that hypoxia conditioning has a greater effect on enhancing VO2peak compared to equivalent normoxic training in the middle-aged and older population. More high-quality RCTs are needed in the future to explore the optimal oxygen concentration and exercise intensity during hypoxia conditioning.

The accuracy of fixed intensity anchors to estimate lactate thresholds in recreational runners

BACKGROUND

Endurance exercise intensities can be categorized into moderate, heavy, and severe domains based on physiological responses during incremental exercise testing. Since the evaluation of metabolic thresholds is not always possible, this study assessed the accuracy of fixed intensity anchors to estimate lactate thresholds.

METHODS

165 (64 females, 101 males) recreational runners performed a maximal incremental treadmill test. The first (LT1) and second (LT2) lactate thresholds were determined as percentages of maximum heart rate (HR), oxygen consumption (VO2), and running speed, alongside the rating of perceived exertion (RPE). Sex-specific mean values were used to determine the threshold intensities and to analyze the error magnitude for each method.

RESULTS

Females had a higher relative HR, VO2, and speed at LT1 compared to males (p < 0.001). In the pooled data, the mean absolute error for estimating LT1 varied from 0.6 to 0.8 km/h for speed and 4.9-7.4 bpm for HR, while LT2 errors ranged from 0.4 to 0.8 km/h and 2.8-5.2 bpm, respectively. The speed-derived estimations yielded the smallest error magnitudes, while the RPE-derived estimations were the least accurate. Estimating the maximum speed increased the respective errors to 1.0 km/h and 8.4 bpm for LT1, and to 1.1 km/h and 6.7 bpm for LT2.

CONCLUSION

LT1 occurred at higher relative intensity in females, suggesting a need for sex-specific intensity anchors. The speed-derived estimates were the most accurate, but the estimation of maximum values impaired the prediction accuracy. Thus, the optimal method also depends on the availability of the maximum values.

Acute fatigue in indoor court-based team sports: A systematic review

Fatigue in team sports has been widely researched, with a number of systematic reviews summarising the acute (i.e., within 48-hours) response in outdoor sports. However, the fatigue response to indoor court-based sports is likely to differ to outdoor sports due to smaller playing fields, harder surfaces, and greater match frequencies, thus should be considered separately to outdoor sports. Therefore, this study aimed to conduct a systematic review on acute fatigue in indoor court-based team-sport, identify methods and markers used to measure acute fatigue, and describe acute fatigue responses. A systematic search of the electronic databases (PubMed, SPORTDiscus, MEDLINE and CINHAL) was conducted from earliest record to June 2023. Included studies investigated either a physical, technical, perceptual, or physiological response taken before and after training, match, or tournament play. One-hundred and eight studies were included, measuring 142 markers of fatigue. Large variability in methods, fatigue markers and timeline of measurements were present. Cortisol (n =  43), creatine kinase (n =  28), countermovement jump (n =  26) and testosterone (n =  23) were the most frequently examined fatigue markers. Creatine kinase displayed the most consistent trend, increasing 10-204% at 24-hours across sports. There is large variability across studies in the methods and markers used to determine acute fatigue responses in indoor court-based team sports. Future researchers should focus on markers that display high reliability and transfer to practice. The robustness of studies may be increased by ensuring appropriate methods and timescale of fatigue marker measurement are used. Further research is required to determine which combination of markers best describes a fatigue response.

Comparative analysis of consistency of adaptations to interval interventions individualized using sport-specific techniques in well-trained soccer players

This study aimed to investigate the uniformity of adaptive changes in cardiorespiratory fitness and anaerobic power to high-intensity interval interventions (HIIT) designed using techniques specified for soccer players. Thirty well-trained athletes (age = 25 ± 3.1 years; body mass = 82.4 ± 3.4 kg; height = 183 ± 2.1 cm) were randomly assigned to two experimental groups engaging in interval intervention individualized using 30-15 Intermittent Fitness Test [HIITvIFT (two sets of 5-8 min intervals, comprising 15 s of running at 95% of VIFT followed by 15 s of passive recovery)], and small-sided game with matched timing (SSG [4 sets of 2.5-4 min 3 v 3 efforts]), as well as an active control group. Before and after a 6-week intervention consisting of three sessions per week, participants underwent a lab-based cardiorespiratory fitness test using breath-by-breath gas analyzer and non-invasive impedance cardiography to evaluate aerobic fitness and cardiac function measures. Also, anaerobic power was measured using lower-body Wingate test. Both interventions resulted in significant enhancement in all measures of cardiorespiratory fitness and anaerobic power over the training period. Analyzing inter-individual variability through determining residuals in individual changes indicated HIITvIFT results in residuals in individual changes in ventilatory threshold (VT [first (VT1) and second (VT2)]), and peak and average power output than SSG (p = 0.02, 0.04, 0.02, and 0.01, respectively). In addition, the change in maximum oxygen uptake, maximal ventilation, and average power output following HIITvIFT was notably greater than SSG (p = 0.002, 0.006, and, 0.019, respectively). There was no significant difference between HIITvIFT and SSG in cardiac hemodynamics (cardiac output and stroke volume). Overall, by facilitating more homogenous stress, HIITvIFT results in more identical physiological demands and more uniform adaptations in ventilatory threshold and anaerobic power than SSG.

Individual variability in lactate response to cycling prescribed using physiological thresholds and peak work rate: a crossover within-participant repeated measures study

PURPOSE

(1) To determine if the blood lactate concentration ([BLa]) response is a repeatable individual trait, and (2) To examine whether threshold-based prescription (THR) reduces interindividual variability in [BLa] response compared to traditional (maximally anchored) exercise prescription (TRAD).

METHOD

A crossover within-participant repeated measures design was used to assess [BLa] during the TRAD and THR exercise in 17 participants (9 M/8F). Participants initially undertook an incremental test to exhaustion to determine peak work rate (WRpeak), a lactate threshold (LT) test and a critical power (CP) test. All baseline tests were repeated twice. Participants then completed 6 15-min bouts of continuous cycling at 65%WRpeak (TRAD; 3 bouts) and 80% of the difference (Δ80) between LT and CP (THR; 3 bouts). [BLa] response was measured at 10 and 15 min of exercise.

RESULTS

Across individuals, there was a wide range in [BLa] response, but within individual responses were repeatable. [BLa] ranges and mean individual 90% confidence interval width (CIw) were as follows: TRAD@10 min = 2.1-9.7 mmol, CIw = 0.5 mmol, THR@10 min = 3.4-9.3 mmol, CIw = 0.6 mmol, TRAD@15 min = 2.2-9.9 mmol, CIw = 0.6 mmol, THR@15 min = 3.6-12.3 mmol, CIw = 0.7 mmol. Levene's tests revealed no significant differences in the variability of [BLa] response between TRAD and THR at 10 min (F = 0.523, p = 0.475) or 15 min (F = 0.351, p = 0.558) of exercise.

CONCLUSION

Our results demonstrate that true interindividual variability in the [BLa] response to exercise exists, but failed to confirm that variability in [BLa] response is reduced with the use of THR.

Student and physiotherapists' perceived abilities to prescribe effective physical activity and exercise interventions: A cross-sectional survey

BACKGROUND

Physical activity, aerobic and resistance training have established benefits to health and wellbeing, with physiotherapists playing a vital role in their promotion.

OBJECTIVES

To capture UK student and graduate physiotherapists (1) knowledge of accepted guidelines and, (2) perceptions of physical activity and exercise prescription in practice.

DESIGN

National cross-sectional online survey.

METHODOLOGY

A survey was conducted online among UK student and graduate physiotherapists from July to December 2021. Quantitative questions included dichotomous (yes/no), multiple-choice, and Likert scale (1-5) formats, alongside open-ended qualitative questions.

RESULTS

Of 305 respondents (18% students, 47% > 10 years' experience), 295 (97%) either "agreed" (n = 64, 21%) or "strongly agreed" (n = 231, 76%) that physical activity was a part of their role. Less than half felt the physiotherapy profession was able to provide effective physical activity (n = 149, 49%, 95% confidence intervals 43 to 54) and aerobic training (130, 43%, 37 to 48). Most knew the weekly minimum adult dosage of physical activity (257, 84%, 80 to 88) and resistance training (267, 88%, 83 to 91) but were generally unable to correctly identify aerobic and resistance training guidelines. Of those who used evidenced based guidelines regularly with patients 72% were not adopting correct guidelines for aerobic (n = 58, 72%, 61 to 80) and 46% for resistance training (n = 45, 46%, 36 to 56). Limited patient appointment duration, inadequate access to facilities and a lack of continuous professional development opportunities were perceived barriers to implementation.

CONCLUSION

Respondents agreed physical activity and exercise are vital treatment modalities, however many lack the knowledge to deliver these interventions in line with contemporary guidelines.

The PREPARE Study: Acceptability and Feasibility of a Telehealth Trimodal Prehabilitation Program for Women with Endometrial Neoplasia

Patients with endometrial neoplasia (EN) often have multiple comorbidities and a higher surgical risk. Prehabilitation programs (PPs) combine various interventions to improve preoperative conditions and reduce impairment due to surgical stress. We conducted a pragmatic pilot study to evaluate the acceptability and feasibility of a trimodal telehealth PP (exercise, nutrition, and psychological support) for EN patients. The participants could select their exercise group: (1) a supervised PP (SPP), group sessions 3×/week; (2) a semi-supervised PP (SSPP), group session 1×/week, training alone 2×/week; or (3) a physical activity counseling session (PACS). Out of the 150 EN patients awaiting surgery screened during the 18 months of the study recruitment, 66% (99/150) were eligible, and 40% consented to participate (SPP, n = 13; SSPP, n = 17; PACS, n = 9). The overall dropout was low (13%; 5/39), with no significant differences across groups. No serious adverse events occurred. We observed a positive impact on different outcomes across the different groups, such as in the Functional Assessment of Cancer Therapy quality of life score (SPP; delta = 6.1 [CI: 0.9; 12.6]) and functional capacity measured using the 30″ sit-to-stand test (PACS delta = 2.4 [CI: 1.2; 3.6]). The same-day hospital leave was high in the SSPP group (54.5%). Our pilot telehealth PP seems to be safe, feasible, and well accepted and may procure clinical and patient-centered gains that need to be confirmed in a larger trial.

Monitoring Sleep and Nightly Recovery with Wrist-Worn Wearables: Links to Training Load and Performance Adaptations

Previous studies on the effects of intensified training on sleep quality/quantity have been somewhat contradictory. Moreover, recreational athletes often track various sleep metrics, and those metrics' actual connections to training adaptations are unknown. This study explored the effects of intensified training on sleep and nightly recovery along with their associations with training adaptations. A total of 24 participants (10 females) performed a 3-week baseline training period (BL), a 2-week overload period (OL), and a 1-week recovery period (REC), which were followed by test days (T1-T3). The endurance performance was assessed with a 3000 m running test. Throughout all of the periods, the nightly recovery information was monitored with a wrist-worn wearable, including sleep quantity and quality, heart rate (HR) and HR variability (HRV), and proprietary parameters combining several parameters and scaling the results individually. In addition, the perceived strain and muscle soreness were evaluated daily. The 3000 m running performance improved from T1 to T2 (-1.2 ± 1.7%, p = 0.006) and from T1 to T3 (-1.7 ± 1.2%, p = 0.002). The perceived strain and muscle soreness increased (p < 0.001) from the final week of the BL to the final week of the OL, but the subjective sleep quality and nightly recovery metrics remained unchanged. The OL average of the proprietary parameter, autonomic nervous system charge ("ANS charge", combining the HR, HRV, and breathing rate), as well as the change in the sleep HR and HRV from the BL to the OL, were associated (p < 0.05) with a change in the 3000 m running time. In conclusion, the subjective recovery metrics were impaired by intensified training, while the sleep and nightly recovery metrics showed no consistent changes. However, there were substantial interindividual differences in nightly recovery, which were also associated with the training adaptations. Therefore, monitoring nightly recovery can help in recognizing individual responses to training and assist in optimizing training prescriptions.

Variability in resistance training trajectories of breast cancer patients undergoing therapy

PURPOSE

In resistance training (RT), the change in volume-load from training sessions (TS) to TS is an indicator of training progress. Resulting growth trajectories are likely to differ between individuals. Understanding this variation is important for exercise planning in general, but even more for clinical populations. We investigated this variation in breast cancer patients undergoing treatment.

METHODS

Data of 69 patients from two randomized controlled trails were investigated. They conducted a 12-week RT program. We fitted a quadratic Bayesian regression model to the baseline standardized volume-load over the course of the intervention. We allowed all parameters to vary both between exercises and between individuals.

RESULTS

We observed a positive linear component of 0.093 (95% uncertainty interval (UI) 0.058 to 0.120) and a negative quadratic component of - 0.002 (95% UI -0.008 to 0.001) for the mean trajectory of the change in volume-load. For the different exercises, we observed a dispersion for both the linear (0.043, 95% UI 0.018 to 0.082) and the quadratic component (0.002, 95% UI < 0.001 to 0.004). Variation between individual appears to be approximately four times larger. We also observed between-exercise variation within individuals. Extrapolation of the regression model indicates training progression stagnates after 20.6 TS (95% UI 14.8 to 44.4).

CONCLUSION

There is substantial variation in RT response between breast cancer patients undergoing tumor therapy and in-between exercises. The non-linear trajectory indicates that training progression will eventually plateau, demanding periodization and timely modification.

TRIAL REGISTRATION

BEATE Study: NCT01106820, Date: April 20, 2010; BEST Study: NCT01468766, Date: November 9, 2011.

The Impact of Running-Based and Drop Jumping Interval Interventions on Cardiorespiratory Fitness and Anaerobic Power of Collegiate Volleyball Players: A Comparative Analysis of Inter-Individual Variability in the Adaptive Responses

This study compared inter-individual variability in the adaptive responses of cardiorespiratory fitness, anaerobic power, and motor abilities of male volleyball players to high-intensity interval training (HIIT) prescribed as repetitive drop jumps (interval jumping) and running-based intervals (interval running). Twenty-four collegiate volleyball players were equally randomized to two training groups executing 11 minutes of interval running or interval jumping during which they ran or repeated drop-jumps for 15 seconds, alternating with 15 seconds of passive recovery. Before and after the 6-week training period, aerobic fitness, cardiac function, and anaerobic power were evaluated using a graded exercise test, impedance cardiography, and a lower-body Wingate test, respectively. Additionally, linear speed, agility, and jumping tests determined motor abilities. Both interventions significantly enhanced maximum oxygen uptake (V̇O2max), velocity associated with V̇O2max, first and second ventilatory thresholds (VT1 & VT2), maximal cardiac output (Q̇max), stroke volume (SVmax), peak and average power output, vertical jump, change of direction, and linear sprint speed. Interval jumping group demonstrated a significantly greater improvement in squat jump (p = 0.001; 95% CI: 2.51-5.42) and countermovement jump (p = 0.001; 95% CI: 2.11-4.61) compared to interval running group. Conversely, interval running group elicited a greater enhancement in sprint speed (p = 0.002; 95% CI: 2.53-5.71) than interval jumping group. Examining the individual residual in the adaptive responses revealed that interval running induced more homogenized adaptations across individuals in VT1 (p = 0.04; 95% CI: 0.03-1.33), Q̇max (p = 0.03; 95% CI: 0.04-1.64), SVmax (p = 0.04; 95% CI: 0.02-1.75), and maximal sprint speed (p = 0.01; 95% CI: 0.72-1.95) in contrast to interval jumping. However, the uniformity of adaptations in countermovement jump in response to interval jumping surpassed that of interval running (p = 0.02; 95% CI: 0.08-1.32). Although both training modalities effectively improved the mentioned variables concurrently, tailoring the HIIT intervention to the reference intensity and training modality specific for each quality may enhance measured quality.

Effect of Fitness Level on Time Course of Recovery After Acute Strength and High-Intensity Interval Training

ABSTRACT

Grammenou, M, Kendall, KL, Wilson, CJ, Porter, T, Laws, SM, and Haff, GG. Effect of fitness level on time course of recovery after acute strength and high-intensity interval training. J Strength Cond Res 38(12): 2055-2064, 2024-The aim was to investigate time course of recovery after acute bouts of strength (STR) and high-intensity interval training (HIIT). A secondary goal was to assess the influence of total fitness score (TFS), composed of handgrip strength and maximum aerobic power on recovery. Twenty-eight resistance-trained individuals completed 8 testing sessions within a 14- to 17-day period. Subjects performed a testing battery comprising isometric midthigh pull (IMTP), countermovement jump (CMJ), and a modified Wingate test (WINmod) at baseline, immediately after exercise, as well as at 6 and 24 hours after the training sessions. A one-way ANOVA was performed to examine time changes after the training sessions. Subjects were then grouped based on their TFS in high, medium, and low groups. To examine the influence of TFS on time course of recovery, we performed a linear mixed-effects model. Statistical significance was set at p < 0.05. Both training sessions resulted in a significant reduction in peak force (PF) that persisted for up to 6 (p < 0.05) and 24 hours (p < 0.001). The STR session showed immediate and 24-hour postexercise declines in jump height and reactive strength index modified (RSImod) compared with baseline. The low TFS group exhibited a significant RSImod reduction immediately after HIIT (p < 0.001), compared with the medium TFS group (p = 0.0002). In the STR session, the high TFS group displayed an increased eccentric displacement during CMJ 24 hours after exercise compared with baseline (p = 0.033). Overall, subjects with high TFS may be able to recover CMJ performance at the same rate as other TFS groups, despite performing more work.

Effects of Short Sprint Interval Training Frequency on Physical and Physiological Performance Adaptations in Male Soccer Players

The study aimed to evaluate the effects of varying frequencies (1 vs. 2 vs. 3) of short sprint interval training (sSIT) on young male soccer players' physical performance and physiological parameters. Forty young male soccer players were randomly assigned to four experimental groups engaging in 36 trials sSIT for a duration of 6 weeks as follows: once weekly (1sSIT = 4 sets of 9 × 5 sec all-out runs), twice weekly (2sSIT = 2 sets of 9 × 5 sec all-out runs), and three times weekly (3sSIT = 2 sets of 6 × 5 sec all-out runs), or an active control group which continued their soccer practice routines. Before and after the 6-week training period, physical performance (countermovement vertical jump, 20-m sprint, Illinois change of direction, Yo-Yo intermittent recovery level 1 [Yo-Yo IR 1] and kicking distance) and physiological parameters (cardiorespiratory fitness, peak and average power output) were evaluated. All sSIT groups demonstrated significant (p < 0.01) and small to very large training effects (i.e., effect size) on measured parameters. More importantly, a comparison of inter-individual variability in the adaptive changes revealed that the 3sSIT group results in lower residuals in changes in cardiorespiratory fitness and anaerobic power, coupled with lower coefficient of variations in the mean group changes and perceived exertion throughout the training period. The findings indicate that incorporating one, two, or three weekly sessions of sSIT into routine soccer training can lead to similar enhancements in soccer players' physiological and performance adaptations. More importantly, higher training frequencies result in more homogenized adaptations among team members by reducing inter-individual variability in the magnitude of the adaptive responses.

Impacts of Square Stepping Exercise on Physical-Cognitive Function, Biomarkers, Body Composition and Mental Health in Healthy Senior Aged 60 and Above: A Systematic Review

Background: The aim of this systematic review is to analyze the effects of Square Stepping Exercise (SSE) on physical and cognitive function in older people, including its effects on biomarkers, body composition and mental health, focusing only on research that assessed the efficacy of SSE-based interventions. Methods: PubMed, Web of Science, Scopus and Cochrane databases were searched from June 2006 to June 2024 according to the PRISMA guidelines. The main search terms used were related to "older people" and "square-stepping exercise". Controlled trials that included at least one intervention group focused on SSE were included. Participants had to be healthy, without physical or cognitive impairment, and the studies published in English or Spanish. The methodological quality of the selected research was assessed using the Physiotherapy Evidence Database (PEDro). Results: Twelve studies were selected from a total of 444 original records, with a total sample size of 577 participants. The health parameters of the participants were homogeneous, with ages ranging from 60 to 80 years. Significant gains were reported in certain physical function assessments, including balance, lower body strength and power, gait speed and flexibility. There were also significant findings in cognitive function, particularly in general cognitive status, focused attention, response time, basic task performance, and executive function. In addition, SSE can improve metrics such as body composition, brain-derived neurotrophic factor (BDNF), and mental health characteristics. Conclusions: SSE has the potential to significantly improve physical function, cognitive performance and body composition, as well as provide mental health benefits and have variable effects on biomarkers and cardiovascular health.

Effects of therapeutic exercise on pain processing in people with chronic non-specific neck pain - A systematic review and meta-analysis

BACKGROUND

Emerging evidence suggests that individuals with chronic non-specific neck pain may experience altered sensory processing, potentially contributing to the modest response to therapeutic exercise treatments.

OBJECTIVE

This systematic review aims to explore the effect of therapeutic exercise on pain processing among patients with chronic non-specific neck pain.

METHODS

A systematic search was conducted in multiple databases (PubMed, EMBASE, CINAHL, PEDro, SportDiscus, and Cochrane CENTRAL) from inception to June 2023. Inclusion criteria included randomized controlled trials (RCT) comparing therapeutic exercise to non-exercise treatments or no treatment. The screening and data extraction was conducted by two reviewers. The methodological quality was evaluated using the PEDro scale and the certainty of evidence using GRADE. The primary outcomes assessed were pressure pain threshold (PPT), temporal summation, and conditioned pain modulation.

RESULTS

Thirteen trials included a total of 948 participants, with 586 in the exercise therapy group and 362 in the non-exercise group. The therapeutic exercise was not superior to non-exercise treatments for both local and PPT in the immediate (MD = 0.13, 95%CI = -0.18 to 0.43), and short-term follow-up (MD = 0.17, 95%CI = -0.27 to 0.61). In the medium term, therapeutic exercise demonstrated a small effect size in increasing local PPT (Kg/cm2) (MD = 0.64, 95%CI = 0.08 to 1.19) compared to non-exercise interventions. The certainty of evidence for these outcomes was very low.

CONCLUSIONS

There is very low certainty of evidence that therapeutic exercise is not superior than non-exercise treatment on pain processing in patients with chronic non-specific neck pain.

Inter-individual differences in muscle damage following a single bout of high-intense whole-body electromyostimulation

Purpose

This brief report aimed to characterize inter-individual training responses following a single session of high-intense whole-body electromyostimulation (WB-EMS) using markers of muscle damage over a period of 72 h.

Methods

Twelve healthy individuals (5 men, 7 women; 32.0 ± 7 years) participated in a single 20-minute high-intensity WB-EMS training session. Markers of muscle damage, creatine kinase (CK) and myoglobin (Mb), were assessed before and immediately after training, as well as at 1.5, 3, 24, 48 and 72 h post-exercise. Lactate levels were determined pre- and post-exercise.

Results

Overall, WB-EMS induced significant CK elevations, peaking at 72 h (18.358 ± 21.380 U/L; p < 0.01), and correlating Mb levels peaking at 48 h (1.509 ± 1.394 ng/dl, p < 0.01). Despite significant inter-individual variability in CK levels, both slow (SR) and fast responders (FR) were identified. FR showed significant increases in CK at all time points post WB-EMS (p < 0.05), whereas CK in SR significantly elevated after 48 h. Post-WB-EMS lactate concentration was identified to predict peak CK and Mb levels (r ≥ 0.65, both p < 0.05).

Conclusion

High-intensity WB-EMS has the potential to induce severe muscle damage, as indicated by elevated levels of CK and Mb. We identified two distinct groups of individuals, SR and FR, indicating variability in response to WB-EMS. Furthermore, we suggest that individual responses to WB-EMS can be predicted based on post-WB-EMS lactate concentration.

The Discrepancy Between External and Internal Load/Intensity during Blood Flow Restriction Exercise: Understanding Blood Flow Restriction Pressure as Modulating Factor

Physical exercise induces acute psychophysiological responses leading to chronic adaptations when the exercise stimulus is applied repeatedly, at sufficient time periods, and with appropriate magnitude. To maximize long-term training adaptations, it is crucial to control and manipulate the external load and the resulting psychophysiological strain. Therefore, scientists have developed a theoretical framework that distinguishes between the physical work performed during exercise (i.e., external load/intensity) and indicators of the body's psychophysiological response (i.e., internal load/intensity). However, the application of blood flow restriction (BFR) during exercise with low external loads/intensities (e.g., ≤ 30% of the one-repetition-maximum, ≤ 50% of maximum oxygen uptake) can induce physiological and perceptual responses, which are commonly associated with high external loads/intensities. This current opinion aimed to emphasize the mismatch between external and internal load/intensity when BFR is applied during exercise. In this regard, there is evidence that BFR can be used to manipulate both external load/intensity (by reducing total work when exercise is performed to exhaustion) and internal load/intensity (by leading to higher physiological and perceptual responses compared to exercise performed with the same external load/intensity without BFR). Furthermore, it is proposed to consider BFR as an additional exercise determinant, given that the amount of BFR pressure can determine not only the internal but also external load/intensity. Finally, terminological recommendations for the use of the proposed terms in the scientific context and for practitioners are given, which should be considered when designing, reporting, discussing, and presenting BFR studies, exercise, and/or training programs.

Glucose ingestion before and after resistance training sessions does not augment ribosome biogenesis in healthy moderately trained young adults

PURPOSE

Resistance training-induced skeletal muscle hypertrophy seems to depend on ribosome biogenesis and content. High glucose treatment may augment ribosome biogenesis through potentiating resistance training-induced adaptations. This was investigated with total RNA and ribosomal RNA abundances as main outcomes, with relevant transcriptional/translational regulators (c-Myc/UBF/rpS6) as a secondary outcome.

METHODS

Sixteen healthy, moderately trained individuals [male/female, n = 9/7; age, 24.1 (3.3)] participated in a within-participant crossover trial with unilateral resistance training (leg press and knee extension, 3 sets of 10 repetitions maximum) and pre- and post-exercise ingestion of either glucose (3 × 30 g, 90 g total) or placebo supplements (Stevia rebaudiana, 3 × 0.3 g, 0.9 g total), together with protein (2 × 25 g, 50 g total), on alternating days for 12 days. Six morning resistance exercise sessions were conducted per condition, and the sessions were performed in an otherwise fasted state. Micro-biopsies were sampled from m. vastus lateralis before and after the intervention.

RESULTS

Glucose ingestion did not have beneficial effects on resistance training-induced increases of ribosomal content (mean difference 7.6% [- 7.2, 24.9], p = 0.34; ribosomal RNA, 47S/18S/28S/5.8S/5S, range 7.6-37.9%, p = 0.40-0.98) or levels of relevant transcriptional or translational regulators (c-MYK/UBF/rpS6, p = 0.094-0.292). Of note, both baseline and trained state data of total RNA showed a linear relationship with UBF; a ∼14% increase in total RNA corresponded to 1 SD unit increase in UBF (p = 0.003).

CONCLUSION

Glucose ingestion before and after resistance training sessions did not augment ribosomal RNA accumulation during twelve days of heavy-load resistance training in moderately trained young adults.

The delta concept does not effectively normalise exercise responses to exhaustive interval training

OBJECTIVES

This study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O2max) are taken into account to normalise relative exercise intensity.

DESIGN

Repeated-measures, within-subjects design with mixed-effects modelling.

METHODS

Eighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O2max: 51.6 ± 5.3 ml·kg-1·min-1) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability.

RESULTS

Greater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively.

CONCLUSIONS

Due to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Monitoring Within-Individual Dose-Response Relationships in Professional Soccer Players: The Importance of Fitness Level

PURPOSE

To (1) examine within-individual player dose-response associations between selected training-load measures and changes in aerobic fitness level via submaximal exercise heart rate (HRex%) and (2) measure the relationships between these dose-response associations with basal HRex% (to study the influence of fitness level on dose-response relationship).

METHODS

During an in-season phase, selected training-load measures including total minutes, total distance, mechanical work (the sum number of accelerations and decelerations > 3 m2), high metabolic load distance, and Edwards' training impulse were collected via Global Positioning System and heart-rate sensors for analyzing accumulated load. A submaximal warm-up test was used repeatedly before and after 9 phases to elicit HRex% and track fitness changes at an individual level.

RESULTS

Negative to positive extensive ranges of within-individual associations were found among players for different metrics (r = -.84 to .89). The relationship between pooled HRex% (basal fitness) and dose-response correlations showed inverse very large (r = -.71) and large (r = -.65) values for accumulated weekly minutes and distance. However, moderate values were found for all other measures (r = -.35 to -.42).

CONCLUSIONS

Individual players show extensive different ranges of dose-response associations with training measures. The dose-response association is influenced by players' fitness level, and players with lower fitness levels show stronger inverse relationships with accumulated minutes and total distance.

HIIT at Home: Enhancing Cardiorespiratory Fitness in Older Adults-A Randomized Controlled Trial

BACKGROUND

This study aimed to investigate the effectiveness of a 6-month home-based high-intensity interval training (HIIT) intervention to improve peak oxygen consumption (V̇O2peak) and lactate threshold (LT) in older adults.

METHODS

Two hundred thirty-three healthy older adults (60-84 years; 54% females) were randomly assigned to either 6-month, thrice-weekly home-based HIIT (once-weekly circuit training and twice-weekly interval training) or a passive control group. Exercise sessions were monitored using a Polar watch and a logbook for objective and subjective data, respectively, and guided by a personal coach. The outcomes were assessed using a modified Balke protocol combining V̇O2peak and LT measures. General linear regression models assessed between-group differences in change and within-group changes for each outcome.

RESULTS

There was a significant between-group difference in the pre-to-post change in V̇O2peak (difference: 1.8 [1.2; 2.3] mL/kg/min; exercise: +1.4 [1.0; 1.7] mL/kg/min [~5%]; control: -0.4 [-0.8; -0.0] mL/kg/min [approximately -1.5%]; effect size [ES]: 0.35). Compared with controls, the exercise group had lower blood lactate concentration (-0.7 [-0.9; -0.4] mmol/L, ES: 0.61), % of peak heart rate (-4.4 [-5.7; -3.0], ES: 0.64), and % of V̇O2peak (-4.5 [-6.1; -2.9], ES: 0.60) at the intensity corresponding to preintervention LT and achieved a higher treadmill stage (% incline) at LT (0.6 [0.3; 0.8]; ES: 0.47), following the intervention.

CONCLUSION

This study highlights the effectiveness of a home-based HIIT intervention as an accessible and equipment-minimal strategy to induce clinically meaningful improvements in cardiorespiratory fitness in older adults. Over 6 months, the exercise group showed larger improvements in all outcomes compared with the control group. Notably, the LT outcome exhibited a more pronounced magnitude of change than V̇O2peak.

A training goal-oriented categorization model of high-intensity interval training

There are various categorization models of high-intensity interval training (HIIT) in the literature that need to be more consistent in definition, terminology, and concept completeness. In this review, we present a training goal-oriented categorization model of HIIT, aiming to find the best possible consensus among the various defined types of HIIT. This categorization concludes with six different types of HIIT derived from the literature, based on the interaction of interval duration, interval intensity and interval:recovery ratio. We discuss the science behind the defined types of HIIT and shed light on the possible effects of the various types of HIIT on aerobic, anaerobic, and neuromuscular systems and possible transfer effects into competition performance. We highlight various research gaps, discrepancies in findings and not yet proved know-how based on a lack of randomized controlled training studies, especially in well-trained to elite athlete cohorts. Our HIIT "toolbox" approach is designed to guide goal-oriented training. It is intended to lay the groundwork for future systematic reviews and serves as foundation for meta-analyses.

Responsiveness of functional performance and muscle strength, power, and size to resistance training: A systematic review

There is a recent and growing interest in assessing differential responders to resistance training (RT) for diverse outcomes. Thus, the individual ability to respond to an intervention for a specific measurement, called responsiveness, remains to be better understood. Thus, the current study aimed to summarize the available information about the effects of RT on functional performance and muscle strength, power, and size in healthy adults, through the prevalence rate in different responsiveness classifications models. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered at the International Prospective Register of Systematic Reviews (PROSPERO, CRD42021265378). PubMed/MEDLINE, Scopus, and Embase databases were systematically searched in October 2023. A total of 13 studies were included, totaling 921 subjects. Only two studies presented a low risk of bias. Regarding the effectiveness of RT, the prevalence rate for non-responders ranged from 0% to 44% for muscle strength, from 0% to 84% for muscle size, and from 0% to 42% for functional performance, while for muscle power, the only study found showed a responsiveness rate of 37%. In conclusion, a wide range of differential responders is described for all variables investigated. However, the evidence summarized in this systematic review suggested some caution while interpreting the findings, since the body of evidence found seems to be incipient, and widely heterogeneous in methodological and statistical aspects.

Optimal Prescription for Superior Outcomes: A Comparative Analysis of Inter-Individual Variability in Adaptations to Small-Sided Games and Short Sprint Interval Training in Young Basketball Players

This study compared the inter-individual variability in adaptive responses to six weeks of small-sided games (SSG) and short sprint interval training (sSIT) in young basketball players. Thirty well-trained young athletes (age: 16.4 ± 0.6 years; stature: 190 ± 8.4 cm; weight: 84.1 ± 8.2 kg) voluntarily participated and were randomly assigned to SSG (3 sets of 5 min 3v3 on full length (28 m) and half-width (7.5 m) court, with 2 minutes of passive recovery in-between), sSIT (3 sets of 12 × 5 s sprinting with 20 s recovery between efforts and 2 min of rest between sets), or CON (routine basketball-specific technical and tactical drills) groups, each of ten. Before and after the training period, participants underwent a series of laboratory- and field-based measurements to evaluate their maximum oxygen uptake (V̇O2max), first and second ventilatory threshold (VT1 and VT2), oxygen pulse, peak and average power output (PPO and APO), linear speed, change of direction (COD), countermovement jump (CMJ), and vertical jump (VJ). Both SSG and sSIT sufficiently stimulated adaptive mechanisms involved in enhancement of the mentioned variables (p < 0.05). However, sSIT resulted in lower residuals in percent changes in V̇O2max (p = 0.02), O2pulse (p = 0.005), VT1 (p = 0.001), PPO (p = 0.03), and linear speed (p = 0.01) across athletes compared to the SSG. Moreover, sSIT resulted in more responders than SSG in V̇O2max (p = 0.02, φ = 0.500), O2pulse (p = 0.003, φ = 0.655), VT1 (p = 0.003, φ = 0.655), VT2 (p = 0.05, φ = 0.436), and linear speed (p = 0.05, φ = 0.420). Our results indicate that sSIT creates a more consistent level of mechanical and physiological stimulus than SSG, potentially leading to more similar adaptations across team members.

Contextualising flexible nonlinear periodization as a person-adaptive behavioral model for exercise maintenance

There is a growing focus on developing person-adaptive strategies to support sustained exercise behaviour, necessitating conceptual models to guide future research and applications. This paper introduces Flexible nonlinear periodisation (FNLP) - a proposed, but underdeveloped person-adaptive model originating in sport-specific conditioning - that, pending empirical refinement and evaluation, may be applied in health promotion and disease prevention settings. To initiate such efforts, the procedures of FNLP (i.e., acutely and dynamically matching exercise demand to individual assessments of mental and physical readiness) are integrated with contemporary health behaviour evidence and theory to propose a modified FNLP model and to show hypothesised pathways by which FNLP may support exercise adherence (e.g., flexible goal setting, management of affective responses, and provision of autonomy/variety-support). Considerations for future research are also provided to guide iterative, evidence-based efforts for further development, acceptability, implementation, and evaluation.

Sex Influences the Extent of Physical Performance Adaptations in Response to Small-Sided Games and Running-Based High-Intensity Interval Training: A Parallel Study Design Involving Men and Women Soccer Players

The aim of this study was two-fold: (i) to compare physical fitness adaptations following small-sided games (SSG) and running-based high-intensity interval training (HIIT), considering sex interactions; and (ii) to describe intra-individual variations of adaptations in both men and women developmental/trained soccer players over an 8-week randomized parallel study design involving 25 women and 27 men. Pre and post-intervention assessments included countermovement jump (CMJ), 10-meter linear sprint test, change-of-direction (COD) deficit, and final velocity at 30-15 Intermittent Fitness Test (VIFT). Significant interactions between time, groups and sex were found in 10-m sprint (F1,48 = 6.042; p = 0.018; ηp2 = 0.112). No significant interactions between time, groups and sex were found in CMJ (F F1,48 = 0.609; p = 0.439; ηp2 = 0.013), COD deficit (F F1,48 = 2.718; p = 0.106; ηp2 = 0.054) and VIFT (F F1,48 = 1.141; p = 0.291; ηp2 = 0.023). Significant interactions were found between time and sex in CMJ (F F1,48 = 29.342; p < 0.001; ηp2= 0.379), 10-m sprint (F F1,48 = 4.359; p = 0.042; ηp2 = 0.083), COD deficit (F F1,48 = 5.066; p = 0.029; ηp2= 0.095) and VIFT (F F1,48 = 11.248; p = 0.002; ηp2 = 0.190). In conclusion, this study suggests similar effects of HIIT in both sexes. However, for women, SSG may entail less efficacy and more inter-individual variability compared to men. Therefore, HIIT could potentially be a better solution for women, whereas both training approaches were equally effective in men.

The impact of individualised versus standardised endurance and resistance training on the fitness-fatness index in inactive adults

OBJECTIVES

The aim of the current study was to investigate the impact of individualised versus standardised combined endurance and resistance training on the fitness-fatness index in physically inactive adults.

DESIGN

Randomised controlled trial.

METHODS

Fifty-four participants aged 21-55 years were randomised into three groups; 1) non-exercise control (n = 18), 2) standardised moderate-intensity continuous training (n = 18), or 3) individualised moderate-intensity continuous training + high-intensity interval training (n = 18). The fitness-fatness index was calculated by dividing cardiorespiratory fitness (expressed as metabolic equivalents) by the waist-to-height ratio. Participants were classified as likely responders to the intervention if a change of ≥1 fitness-fatness index unit was achieved.

RESULTS

The individualised group showed the greatest fitness-fatness index improvement (between group difference p < 0.001), with 100 % of this group classified as likely responders, compared to the standardised (68 %) and non-exercise control (0 %) groups.

CONCLUSIONS

An individualised, threshold-based exercise programme may produce more favourable changes in the fitness-fatness index than a standardised exercise programme.

Optimal homeostatic stress to maximize the homogeneity of adaptations to interval interventions in soccer players

This study examined the uniformity of adaptations in cardiorespiratory fitness and bio-motor abilities by analyzing individual responses to measures representing the mentioned qualities. Twenty-four male well-trained soccer players (Age = 26 ± 4 years; stature = 181 ± 3.8; Weight = 84 ± 6.1) were randomized to two groups performing short sprint interval training [sSIT (3 sets of 10 × 4 s all-out sprints with 20 s of recovery between efforts and 3 min of rest intervals between sets)] or a time-matched small-sided game [SSG (3 sets of 3 v 3 efforts in a 20 × 15 m area with 3 min of relief in-between)]. Before and after the 6-week training period, aerobic fitness indices, cardiac hemodynamics, and anaerobic power were assessed through a graded exercise test utilizing a gas collection system, noninvasive impedance cardiography, and a lower-body Wingate test, respectively. Also, sport-specific bio-motor abilities were determined by measuring linear speed, change of direction, and jumping ability. Comparing inter-individual variability in the adaptive changes by analyzing residuals in individual adaptations indicated that sSIT induces more uniform changes in the first and second ventilatory threshold (VT1 & VT2), stroke volume, and peak power output across team members than SSG. SSG also yielded lower proportions of responders in V ˙ O 2 ⁡ max , VT1, VT2, peak, and average power output compared to sSIT. Additionally, the coefficient of variation in mean group changes in measures of aerobic fitness and bio-motor abilities in response to sSIT were lower than in SSG. Short sprint interval training induces more homogenized adaptations in measures of cardiorespiratory fitness and anaerobic power than small-sided games across team members.

Mind to move: Differences in running biomechanics between sensing and intuition shod runners

Delving into the complexities of embodied cognition unveils the intertwined influence of mind, body, and environment. The connection of physical activity with cognition sparks a hypothesis linking motion and personality traits. Hence, this study explored whether personality traits could be linked to biomechanical variables characterizing running forms. To do so, 80 runners completed three randomized 50-m running-trials at 3.3, 4.2, and 5m/s during which their running biomechanics [ground contact time (tc), flight time (tf), duty factor (DF), step frequency (SF), leg stiffness (kleg), maximal vertical ground reaction force (Fmax), and maximal leg compression of the spring during stance (ΔL)] was evaluated. In addition, participants' personality traits were assessed through the Myers-Briggs Type Indicator (MBTI) test. The MBTI classifies personality traits into one of two possible categories along four axes: extraversion-introversion; sensing-intuition; thinking-feeling; and judging-perceiving. This exploratory study offers compelling evidence that personality traits, specifically sensing and intuition, are associated with distinct running biomechanics. Individuals classified as sensing demonstrated a more grounded running style characterized by prolonged tc, shorter tf, higher DF, and greater ΔL compared to intuition individuals (p≤0.02). Conversely, intuition runners exhibited a more dynamic and elastic running style with a shorter tc and higher kleg than their sensing counterparts (p≤0.02). Post-hoc tests revealed a significant difference in tc between intuition and sensing runners at all speeds (p≤0.02). According to the definition of each category provided by the MBTI, sensing individuals tend to focus on concrete facts and physical realities while intuition individuals emphasize abstract concepts and patterns of information. These results suggest that runners with sensing and intuition personality traits differ in their ability to use their lower limb structures as springs. Intuition runners appeared to rely more in the stretch-shortening cycle to energetically optimize their running style while sensing runners seemed to optimize running economy by promoting more forward progression than vertical oscillations. This study underscores the intriguing interplay between personality traits of individuals and their preferred movement patterns.

Individualizing Basketball-Specific Interval Training Using Anaerobic Speed Reserve: Effects on Physiological and Hormonal Adaptations

PURPOSE

We compared the adaptive responses to supramaximal high-intensity interval training (HIIT) individualized according to anaerobic speed reserve (ASR), the 30-15 Intermittent Fitness Test (VIFT), and velocity associated with maximum oxygen uptake (MAS) to determine which approach facilitates more identical adaptations across athletes with different profiles.

METHODS

Thirty national-level basketball players (age = 28.4 [5] y; body mass = 88.9 [6.3] kg; height = 190 [4.8] cm) were randomly assigned to 3 training groups performing 2 sets of 4, 6, 8, 6, 8, and 10-minute runs (from first to sixth week, respectively), consisting of 15-second running at Δ%20ASR (MAS + 0.2 × ASR), 95%VIFT, and 120%MAS, with 15 seconds recovery between efforts and a 3-minute relief between sets.

RESULTS

All 3 interval interventions significantly (P < .05) enhanced maximum oxygen uptake (V˙O2max), oxygen pulse (V˙O2/HR), first and second ventilatory threshold (VT1 and VT2), cardiac output (Q˙max), stroke volume, peak and average power output, testosterone levels, and testosterone-to-cortisol ratio following the training period. Different values of interindividual variability (coefficient of variation) for the percentage changes of the measured variables were observed in response to HIITASR, HIITvIFT, and HIITMAS for V˙O2max (8.7%, 18.8%, 34.6%, respectively), V˙O2/HR (9.5%, 15.0%, 28.6%), VT1 (9.6%, 19.6%, 34.6%), VT2 (21.8%, 32.4%, 56.7%), Q˙max (8.2%, 16.9%, 28.8%), stroke volume (7.9%, 15.2%, 23.5%), peak power output (20%, 22%, 37.3%), average power output (21.1%, 21.3%, 32.5%), testosterone (52.9%, 61.6%, 59.9%), and testosterone-to-cortisol ratio (55.1%, 59.5%, 57.8%).

CONCLUSIONS

Supramaximal HIIT performed at Δ%20ASR resulted in more uniform physiological adaptations than HIIT interventions prescribed using VIFT or MAS. Although hormonal changes do not follow this approach, all the approaches induced an anabolic effect.

Modelling inter-individual variability in acute and adaptive responses to interval training: insights into exercise intensity normalisation

PURPOSE

To investigate the influence of exercise intensity normalisation on intra- and inter-individual acute and adaptive responses to an interval training programme.

METHODS

Nineteen cyclists were split in two groups differing (only) in how exercise intensity was normalised: 80% of the maximal work rate achieved in an incremental test (% W ˙ max) vs. maximal sustainable work rate in a self-paced interval training session (% W ˙ max-SP). Testing duplicates were conducted before and after an initial control phase, during the training intervention, and at the end, enabling the estimation of inter-individual variability in adaptive responses devoid of intra-individual variability.

RESULTS

Due to premature exhaustion, the median training completion rate was 88.8% for the % W ˙ max group, but 100% for the % W ˙ max-SP the group. Ratings of perceived exertion and heart rates were not sensitive to how intensity was normalised, manifesting similar inter-individual variability, although intra-individual variability was minimised for the % W ˙ max-SP group. Amongst six adaptive response variables, there was evidence of individual response for only maximal oxygen uptake (standard deviation: 0.027 L·min-1·week-1) and self-paced interval training performance (standard deviation: 1.451 W·week-1). However, inter-individual variability magnitudes were similar between groups. Average adaptive responses were also similar between groups across all variables.

CONCLUSIONS

To normalise completion rates of interval training, % W ˙ max-SP should be used to prescribe relative intensity. However, the variability in adaptive responses to training may not reflect how exercise intensity is normalised, underlining the complexity of the exercise dose-adaptation relationship. True inter-individual variability in adaptive responses cannot always be identified when intra-individual variability is accounted for.

Blood pressure responsiveness to resistance training in the hypertensive older adult: a randomized controlled study

Different lifestyle changes have been employed to improve clinical hypertension. However, there is scarce evidence on the blood pressure responsiveness to resistance training (RT) in hypertensive older adults. Consequently, little is known about some participants clinically reducing blood pressure and others not. Thus, we investigate the effects and responsiveness of RT on blood pressure in hypertensive older adults. We secondarily evaluated the biochemical risk factors for cardiovascular disease and functional performance. Older participants with hypertension were randomly assigned into RT (n = 27) and control group (n = 25). Blood pressure, functional performance (timed up and go, handgrip strength, biceps curl and sit-to-stand), fasting glucose, and lipid profiles were evaluated preintervention and postintervention. The statistic was performed in a single-blind manner, the statistician did not know who was the control and RT. RT was effective in reducing systolic blood pressure (SBP) (pre 135.7 ± 14.7; post 124.7 ± 11.0; P  < 0.001) and the responses to RT stimuli varied noticeably between hypertensive older adults after 12 weeks. For example, 13 and 1 responders displayed a minimal clinical important difference for SBP attenuation (10.9 mmHg) in the RT and control groups, respectively. RT improved the functional performance of older people with hypertension, while no differences were found in biochemical parameters (triglycerides, HDL, LDL, fasting glucose) after 12 weeks. In conclusion, responses to RT stimuli varied noticeably between hypertensive individuals and RT was effective in reducing SBP.

Effects of Individualized Exercise on Risk Factors of Metabolic Syndrome: A Scoping Review

Exercise intervention is effective in alleviating the severity of metabolic syndrome (MetS). However, the results of previous studies on the effect of exercise on MetS have demonstrated considerable individual variability in response to a specific dose of exercise, which was attributed to the lack of a personalized approach to exercise prescription. It is essential to consider individual factors to enhance the effectiveness of exercise in addressing MetS. This scoping review assesses the effectiveness of individualized exercise on the risk factors associated with MetS. Various databases and articles were examined based on eligibility criteria and nine studies were chosen for this review. Personal and adjusted factors were predominantly analyzed to tailor exercise prescriptions to individual needs. This review proposes that personal factors can be classified into three categories: fixed factors, adaptation factors, and response factors, considering both clinical and exercise science perspectives. It also suggests that a two-way communication approach between specialists and individuals is more effective for prescribing exercise to address MetS compared to a one-way method. A one-way communication approach relies solely on an expert's decision, even whether or not he or she fully considers a client's lifestyle and preferences. If the individualized selection of exercise prescriptions is achieved through two-way communication between specialists and subjects, significant improvements can be expected in terms of both MetS severity and exercise adherence.

Uniform Homeostatic Stress Through Individualized Interval Training Facilitates Homogeneous Adaptations Across Rowers With Different Profiles

PURPOSE

This study compared the effects of individualizing supramaximal interval rowing interventions using anaerobic power reserve (APR [high-intensity interval training (HIIT) prescribed according to individual APR (HIITAPR)]) and power associated with maximal oxygen uptake (WV˙O2max [HIIT prescribed based on the individual WV˙O2max (HIITW)]) on the homogeneity of physiological and performance adaptations.

METHODS

Twenty-four well-trained rowers (age 24.8 [4.3] y, stature 182.5 [3] cm, body mass 86.1 [4.3]) were randomized into interventions consisting of 4 × 30-second intervals at 130%APR (WV˙O2max + 0.3 × maximal sprint power) with weekly progression by increasing the number of repetitions per set (5, 6, 7, 8, 9, and 10, from first to sixth session) and the same sets and repetitions with the intensity described as 130% WV˙O2max. The work-to-recovery ratio was 1:1 for repetitions and 3 minutes between sets. Responses of aerobic fitness indices, power output, cardiac hemodynamics, locomotor abilities, and time-trial performance were examined.

RESULTS

Both HIITAPR and HIITW interventions significantly improved V˙O2max, lactate threshold, cardiac hemodynamics, and 2000-m performance, with no between-groups difference in changes over time. However, HIITAPR resulted in a lower interindividual variability in adaptations in V˙O2max and related physiological parameters, but this is not the case for athletic performance, which can depend on a multitude of factors beyond physiological parameters.

CONCLUSIONS

Results demonstrated that expressing supramaximal interval intensity as a proportion of APR facilitates imposing the same degrees of homeostatic stress and leads to more homogeneous physiological adaptations in maximal variables when compared to prescribing a supramaximal HIIT intervention using WV˙O2max. However, lower interindividual variability would be seen in submaximal variables if HIIT interventions were prescribed using WV˙O2max.

Frequentist, Bayesian Analysis and Complementary Statistical Tools for Geriatric and Rehabilitation Fields: Are Traditional Null-Hypothesis Significance Testing Methods Sufficient?

Null hypothesis significant testing (NHST) is the dominant statistical approach in the geriatric and rehabilitation fields. However, NHST is routinely misunderstood or misused. In this case, the findings from clinical trials would be taken as evidence of no effect, when in fact, a clinically relevant question may have a "non-significant" p-value. Conversely, findings are considered clinically relevant when significant differences are observed between groups. To assume that p-value is not an exclusive indicator of an association or the existence of an effect, researchers should be encouraged to report other statistical analysis approaches as Bayesian analysis and complementary statistical tools alongside the p-value (eg, effect size, confidence intervals, minimal clinically important difference, and magnitude-based inference) to improve interpretation of the findings of clinical trials by presenting a more efficient and comprehensive analysis. However, the focus on Bayesian analysis and secondary statistical analyses does not mean that NHST is less important. Only that, to observe a real intervention effect, researchers should use a combination of secondary statistical analyses in conjunction with NHST or Bayesian statistical analysis to reveal what p-values cannot show in the geriatric and rehabilitation studies (eg, the clinical importance of 1kg increase in handgrip strength in the intervention group of long-lived older adults compared to a control group). This paper provides potential insights for improving the interpretation of scientific data in rehabilitation and geriatric fields by utilizing Bayesian and secondary statistical analyses to better scrutinize the results of clinical trials where a p-value alone may not be appropriate to determine the efficacy of an intervention.

COVID-19 National Football League (NFL) Injury Analysis: Follow-Up Study

Background

In 2020, COVID-19 spread across the world and brought normal daily life to a halt, causing the shutdown of nearly everything in order to prevent its spread. The National Football League (NFL) similarly experienced shutdowns and the resulting effects, leaving athletes unable to train in some of the most advanced facilities with many of the best trainers in the world. A previous study, titled COVID-19 Return to Sport: NFL Injury Prevalence Analysis, determined that there was increased injury prevalence during the 2020 season, likely due to decreased physiological adaptations within athletes' bodies as a result of facility shutdowns. Understanding injury epidemiology is vital to the prevention of injuries and the development of return-to-play protocols.

Objective

The objective of this study is to perform a follow-up study to COVID-19 Return to Sport: NFL Injury Prevalence Analysis in order to examine the longitudinal effects of the COVID-19 pandemic on injury epidemiology. This study examines if there was a recovery to baseline levels of injuries or if there are still lingering effects from the COVID-19 pandemic-induced spike in injuries.

Methods

To determine if there was change in the number of injuries for each season, injury tallies collected from the 17-week-long 2018, 2019, and 2020 NFL regular seasons were compared with those from the 18-week-long 2021 and 2022 NFL regular seasons. A Kruskall-Wallis test with post hoc Dunn analysis was conducted to compare the rate of injuries per team per week between each of the 2018, 2019, 2020, 2021, and 2022 regular seasons.

Results

The Kruskall-Wallis test revealed an H statistic of 32.61 (P<.001) for the comparison of the injury rates across the 5 seasons. The post hoc Dunn analysis showed that 2020 had a statistically significant difference when compared with each of the 2018 (P<.001), 2019 (P=.04), 2021 (P=.02), and 2022 (P=.048) seasons. The 2019 season showed no statistical significance when compared with the 2021 (P=.23) and 2022 (P=.13) seasons.

Conclusions

The results of this follow-up study, combined with the previous study, show that extended training interruptions stemming from COVID-19 in 2020 induced detraining and led to increased injuries. Additionally, the results of this study show that retraining can occur, resulting in the development of injury protective factors, as injury rates returned to baseline levels after 2020. This is the first large-scale and long-term opportunity to demonstrate the effects of these principles and how they are important to understanding injury epidemiology.

Higher resistance training volume offsets muscle hypertrophy nonresponsiveness in older individuals

The magnitude of muscle hypertrophy in response to resistance training (RT) is highly variable between individuals (response heterogeneity). Manipulations in RT variables may modulate RT-related response heterogeneity; yet, this remains to be determined. Using a within-subject unilateral design, we aimed to investigate the effects of RT volume manipulation on whole muscle hypertrophy [quadriceps muscle cross-sectional area (qCSA)] among nonresponders and responders to a low RT dose (single-set). We also investigated the effects of RT volume manipulation on muscle strength in these responsiveness groups. Eighty-five older individuals [41M/44F, age = 68 ± 4 yr; body mass index (BMI) = 26.4 ± 3.7 kg/m2] had one leg randomly allocated to a single (1)-set and the contralateral leg allocated to four sets of unilateral knee-extension RT at 8-15 repetition maximum (RM) for 10-wk 2 days/wk. Pre- and postintervention, participants underwent magnetic resonance imaging (MRI) and unilateral knee-extension 1-RM strength testing. MRI typical error (2× TE = 3.27%) was used to classify individuals according to responsiveness patterns. n = 51 were classified as nonresponders (≤2× TE) and n = 34 as responders (>2× TE) based on pre- to postintervention change qCSA following the single-set RT protocol. Nonresponders to single-set training showed a dose response, with significant time × set interactions for qCSA and 1-RM strength, indicating greater gains in response to the higher volume prescription (time × set: P < 0.05 for both outcomes). Responders improved qCSA (time: P < 0.001), with a tendency toward higher benefit from the four sets RT protocol (time × set: P = 0.08); on the other hand, 1-RM increased similarly irrespectively of RT volume prescription (time × set: P > 0.05). Our findings support the use of higher RT volume to mitigate nonresponsiveness among older adults.NEW & NOTEWORTHY Using a within-subject unilateral design, we demonstrated that increasing resistance training (RT) volume may be a simple, effective strategy to improve muscle hypertrophy and strength gains among older adults who do not respond to low-volume RT. In addition, it could most likely be used to further improve hypertrophic outcomes in responders.

The intensity paradox: A systematic review and meta-analysis of its impact on the cardiorespiratory fitness of older adults

AIM

The present systematic review and meta-analysis aimed to compare the effect of moderate- versus high-intensity aerobic exercise on cardiorespiratory fitness (CRF) in older adults, taking into account the volume of exercise completed.

METHODS

The databases MEDLINE (Ovid), EMBASE (Ovid), and CENTRAL (Cochrane Library) were searched to identify randomized controlled trials (RCTs). Two reviewers extracted data and assessed bias. Comprehensive Meta-Analysis software calculated overall effect size, intensity differences, and performed meta-regression analyses using pre-to-post intervention or change scores of peak oxygen uptake (V̇O2 peak). The review included 23 RCTs with 1332 older adults (intervention group: n = 932; control group: n = 400), divided into moderate-intensity (435 older adults) and high-intensity (476 older adults) groups.

RESULTS

Meta-regression analysis showed a moderate, but not significant, relationship between exercise intensity and improvements in V̇O2 peak after accounting for the completed exercise volume (β = 0.31, 95% CI = [-0.04; 0.67]). Additionally, studies comparing moderate- versus high-intensity revealed a small, but not significant, effect in favor of high-intensity (Hedges' g = 0.20, 95% CI = [-0.02; 0.41]). Finally, no significant differences in V̇O2 peak improvements were found across exercise groups employing various methods, modalities, and intensity monitoring strategies.

CONCLUSION

Findings challenge the notion that high-intensity exercise is inherently superior and indicate that regular aerobic exercise, irrespective of the specific approach and intensity, provides the primary benefits to CRF in older adults. Future RCTs should prioritize valid and reliable methodologies for monitoring and reporting exercise volume and adherence among older adults.

Assessment of inter-individual variability in hamstring muscle recovery after a sport-specific sprint training in women and men

Background: Hamstring muscles are most affected by multiple sprint-based sports as a result of muscle strain during sprinting, leading to reduced performance and increased risk of injury. Therefore, the purpose of the study was to assess inter-individual variability in hamstrings recovery after a sport-specific repeated-sprint training (RST), through sprint-specific markers of muscle recovery and associated muscle damage biomarkers in women and men. Methods: Healthy females (n = 14) and males (n = 15) underwent 10 repeated 40-m sprints with a 3-min rest pause between each repetition. Force-generating capacity (FGC) by the 90° hip :20° knee test and range of motion Jurdan test, together with serum biomarkers [sarcomeric mitochondrial creatine kinase (sMtCK), oxidative stress, irisin] were tested at baseline and 24-, 48- and 72-h post-exercise through a repeated measures design. Participants were classified according to FGC loss into high responders (HR) and low responders (LR). Results: 21 individuals (10 females, 11 males) were classified as HR (FGC loss >20% and recovery >48 h), while 8 individuals (4 females, 4 males) were classified as LR. HR individuals showed unrecovered maximal voluntary isometric contraction (MVIC) torque until 72 h post-training (p = 0.003, np 2 = 0.170), whereas only HR males showed decreased range of motion (p = 0.026, np 2 = 0.116). HR individuals also showed increased sMtCK (p = 0.016, np 2 = 0.128), oxidative stress (p = 0.038, np 2 = 0.106) and irisin (p = 0.019, np 2 = 0.123). Conclusion: There is inter-individual variability in the muscular response to a sport-specific RST, identifiable by MVIC torque assessment. The findings support that the 90° hip :20° knee test is a powerful indirect test to screen hamstrings recovery in both women and men, in a cost-effective way. However, the Jurdan test might not be able to monitor hamstrings recovery in sportswomen after RST. Decreases in muscle capacity are linked to damage to muscle sarcolemma and mitochondria until 72 h post-exercise. Overall, 72 h will not be adequate time to restore hamstrings structure and function after a sport-specific RST in both female and male responders.

Response rates and associated factors after a multicomponent intervention in frail older adults with diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) and frailty are associated with functional decline in older population.

OBJECTIVE

To explore the individual response to a multimodal intervention on functional performance.

DESIGN

A cluster-randomised multicentre clinical trial.

SETTING

Outpatients in hospital or primary care.

SUBJECTS

843 (77.83 years, 50.65% men) prefrail and frail individuals ≥70 years with T2DM.

METHODS

Participants were allocated to usual care group (UCG) or a multicomponent intervention group (IG): 16-week progressive resistance training, seven nutritional and diabetological educational sessions and achievement of glycated haemoglobin (7-8%) and blood pressure (<150 mmHg) targets. Functional performance was assessed with the Short Physical Performance Battery (SPPB) at 1 year. We used multivariate binomial and multinomial logistic regression models to explore the effect of the IG, and adherence on the outcomes studied, in several adjusted models.

RESULTS

53.7% in the IG versus 38.0% in the UCG improved by at least 1 point in their SPPB score [OR (95% CI): 2.07 (1.43, 2.98), P value <0.001]. Age, SPPB score and number of frailty criteria met decreased the probability of improving the SPPB score. Factors associated with worsening were pertaining to IG (decreased), age, SPPB score and the number of frailty criteria (increased). An adherence ≥84% was needed to achieve benefits, reaching the peak in the probability of improving SPPB when this was ≥85% [OR(95%CI): 2.38 (1.29, 4.79), P value 0.014].

CONCLUSIONS

Factors predicting the likelihood of improvement in a multimodal programme in pre-frail and frail older adults with diabetes are age, basal SPPB score, the number of frailty criteria and adherence.

Sleep, Nutrition, and Injury Risk in Adolescent Athletes: A Narrative Review

This narrative review explores the impact of sleep and nutrition on injury risk in adolescent athletes. Sleep is viewed as essential to the recuperation process and is distinguished as an active participant in recovery through its involvement in growth, repair, regeneration, and immunity. Furthermore, the literature has shown that the sleep of athletes impacts elements of athletic performance including both physical and cognitive performance, recovery, injury risk, and mental well-being. For sleep to have a restorative effect on the body, it must meet an individual's sleep needs whilst also lasting for an adequate duration and being of adequate quality, which is age-dependent. The literature has suggested that athletes have increased sleep needs compared to those of the general population and thus the standard recommendations may not be sufficient for athletic populations. Therefore, a more individualised approach accounting for overall sleep health may be more appropriate for addressing sleep needs in individuals including athletes. The literature has demonstrated that adolescent athletes achieve, on average, ~6.3 h of sleep, demonstrating a discrepancy between sleep recommendations (8-10 h) and actual sleep achieved. Sleep-wake cycles undergo development during adolescence whereby adaptation occurs in sleep regulation during this phase. These adaptations increase sleep pressure tolerance and are driven by the maturation of physiological, psychological, and cognitive functioning along with delays in circadian rhythmicity, thus creating an environment for inadequate sleep during adolescence. As such, the adolescent period is a phase of rapid growth and maturation that presents multiple challenges to both sleep and nutrition; consequently, this places a significant burden on an adolescent athletes' ability to recover, thus increasing the likelihood of injury. Therefore, this article aims to provide a comprehensive review of the available literature on the importance of sleep and nutrition interactions in injury risk in adolescent athletes. Furthermore, it provides foundations for informing further investigations exploring the relation of sleep and nutrition interactions to recovery during adolescence.

Building Bridges Instead of Putting Up Walls: Connecting the "Teams" to Improve Soccer Players' Support

The increase in the economic value of soccer occurred in parallel with an increase in competing demands. Therefore, clubs and federations evolved to greater specialization (e.g., state-of-the-art facilities and high-profile expertise staff) to support players' performance and health. Currently, player preparation is far from exclusively club or national team centered, and the lack of control in each player's environment can be more prevalent than expected. For example, an elite group of professional players faces disruptions in the season club-oriented planification due to involvement in national teams. Moreover, as elite players' financial resources grow, it is common for them to employ specialized personal staff (e.g., strength and conditioning, nutritionist, and sports psychologist) to assist in their preparation, resulting in complex three-fold relationships (i.e., club, player's staff, national team). Although efforts have been made to improve communication with and transition from the club to the national team supervision, this new reality (club-players' staff) may generate serious compound role-related problems and difficulties in monitoring load and training adaptation and having a unified message. Therefore, efforts must be implemented to ensure a more informed management of the players' performance environment, where the existence and impact of these various personal staff are considered to avoid a long-term non-zero sum for all intervening parties. If left unchecked, current professional thinking may collide or overlap, potentially triggering conflict escalation and impairing athletic performance or health, especially if effective communication routes are not adequately established. Moreover, diluted personal responsibility regarding performance may ensue, resulting in decreased productivity from all involved, which may cause more harm than benefits for the player's overall health and performance. This emerging reality calls for developing a joint working framework (i.e., between the player's personalized support team and the clubs' team) and better managing of a player-centered process.

Personalized redox biology: Designs and concepts

Personalized interventions are regarded as a next-generation approach in almost all fields of biomedicine, such as clinical medicine, exercise, nutrition and pharmacology. At the same time, an increasing body of evidence indicates that redox processes regulate, at least in part, multiple aspects of human physiology and pathology. As a result, the idea of applying personalized redox treatments to improve their efficacy has gained popularity among researchers in recent years. The aim of the present primer-style review was to highlight some crucial yet underappreciated methodological, statistical, and interpretative concepts within the redox biology literature, while also providing a physiology-oriented perspective on personalized redox biology. The topics addressed are: (i) the critical issue of investigating the potential existence of inter-individual variability; (ii) the importance of distinguishing a genuine and consistent response of a subject from a chance finding; (iii) the challenge of accurately quantifying the effect of a redox treatment when dealing with 'extreme' groups due to mathematical coupling and regression to the mean; and (iv) research designs and analyses that have been implemented in other fields, and can be reframed and exploited in a redox biology context.

The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders

The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O2 peak improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O2 peak responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %.

The relationships between ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance characteristics in professional soccer players

BACKGROUND

Current research on athletic performance focuses on genetic variants that contribute significantly to individuals' performance. ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms are variants frequently associated with athletic performance among different populations. However, there is limited research examining the pre-and post-test results of some variants of athletic performance in soccer players. Therefore, the presented research is to examine the relationships between the ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance improvement rates in adaptations to six weeks of training in elite soccer players using some athletic performance tests.

METHODOLOGY

Twenty-two soccer players between the ages of 18 and 35 voluntarily participated in the study. All participants were actively engaged in a rigorous six-day-a-week training program during the pre-season preparation period. Preceding and following the training program, a battery of diverse athletic performance tests was administered to the participants. Moreover, Genomic DNA was extracted from oral epithelial cells using the Invitrogen DNA isolation kit (Invitrogen, USA), following the manufacturer's protocol. Genotyping was conducted using real-time PCR. To assess the pre- and post-test performance differences of soccer players, the Wilcoxon Signed Rank test was employed.

RESULTS

Upon analyzing the results of the soccer players based on the ACTN3 genotype variable, it was observed that there were no statistically significant differences in the SJ (Squat Jump), 30m sprint, CMJ (Counter Movement Jump), and DJ (Drop Jump) performance tests (p > 0.05). However, a statistically significant difference was identified in the YOYO IRT 2 (Yo-Yo Intermittent Recovery Test Level 2) and 1RM (One Repetition Maximum) test outcomes (YOYO IRT 2: CC, CT, and TT, p = 0.028, 0.028, 0.008, 0.000, respectively; 1RM: CC, CT, and TT, p = 0.010, 0.34, 0.001, respectively). Regarding the PPARA-α genotype variable, the statistical analysis revealed no significant differences in the SJ, 30m sprint, CMJ, and DJ performance tests (p > 0.05). Nevertheless, a statistically significant difference was observed in the YOYO IRT 2 and 1RM test results (YOYO IRT 2: CC, CG p = 0.001, 0.020; 1RM: CC, p = 0.000) CONCLUSIONS: The current study demonstrated significant enhancements in only YOYO INT 2 and 1RM test outcomes across nearly all gene variants following the six-day-a-week training program. Other performance tests, such as the 30m sprint, SJ, CMJ, and DJ tests did not exhibit statistically significant differences. These findings contribute novel insights into the molecular processes involving PPARA-α rs4253778 and ACTN3 rs1815739 that underpin enhancements in endurance (YOYO INT 2) and maximal strength (1RM) aspects of athletic performance. However, to comprehensively elucidate the mechanisms responsible for the association between these polymorphisms and athletic performance, further investigations are warranted. It is thought that the use of field and genetic analyses together to support each other will be an important detail for athletes to reach high performance.

Early morning run-training results in enhanced endurance performance adaptations in mice

Time-of-day differences in acute exercise performance in mice are well established with late active phase (afternoon) runners exhibiting significantly greater endurance performance compared to early active phase (morning) runners. In this study, we asked if performance adaptations would be different when training for 6 weeks at two different times of day, and if this corresponds to steady state changes in the phase of peripheral tissue clocks. To address these questions, we endurance trained female PER2::Luciferase mice, at the same relative workload, either in the morning, at ZT13, or in the afternoon, at ZT22. Then, after training, we recorded luminescence from tissues of PER2::Luciferase mice to report timing of tissue clocks in several peripheral tissues. After 6 weeks, we found that both groups exhibited significant improvements in maximal endurance capacity (total treadmill work)(p < 0.0001), but the morning runners exhibited an enhanced rate of adaptation as there was no detectable difference in maximal endurance capacity (p = 0.2182) between the morning and afternoon runners. In addition, morning and afternoon runners exhibited divergent clock phase shifts with a significant 5-hour phase advance in the EDL (p < 0.0001) and soleus (p < 0.0001) of morning runners, but a phase delay in the EDL (p < 0.0001) and Soleus (p < 0.0001) of afternoon runners. Therefore, our data demonstrate that morning training enhances endurance adaptations compared to afternoon training in mice, and we suggest this is due to phase advancement of muscle clocks to better align metabolism with exercise performance.

Inter-individual variability in redox and performance responses after antioxidant supplementation: A randomized double blind crossover study

AIM

We aimed to investigate the inter-individual variability in redox and physiological responses of antioxidant-deficient subjects after antioxidant supplementation.

METHODS

Two hundred individuals were sorted by plasma vitamin C levels. A low vitamin C group (n = 22) and a control group (n = 22) were compared in terms of oxidative stress and performance. Subsequently, the low vitamin C group received for 30 days vitamin C (1 g) or placebo, in randomized, double-blind, crossover fashion, and the effects were examined through a mixed-effects model, while individual responses were calculated.

RESULTS

The low vitamin C group exhibited lower vitamin C (-25 μmol/L; 95%CI[-31.7, -18.3]; p < 0.001), higher F2 -isoprostanes (+17.1 pg/mL; 95%CI[6.5, 27.7]; p = 0.002), impaired VO2max (-8.2 mL/kg/min; 95%CI[-12.8, -3.6]; p < 0.001) and lower isometric peak torque (-41.5 Nm; 95%CI[-61.8, -21.2]; p < 0.001) compared to the control group. Regarding antioxidant supplementation, a significant treatment effect was found in vitamin C (+11.6 μmol/L; 95%CI[6.8, 17.1], p < 0.001), F2 -isoprostanes (-13.7 pg/mL; 95%CI[-18.9, -8.4], p < 0.001), VO2max (+5.4 mL/kg/min; 95%CI[2.7, 8.2], p = 0.001) and isometric peak torque (+18.7; 95%CI[11.8, 25.7 Nm], p < 0.001). The standard deviation for individual responses (SDir) was greater than the smallest worthwhile change (SWC) for all variables indicating meaningful inter-individual variability. When a minimal clinically important difference (MCID) was set, inter-individual variability remained for VO2max , but not for isometric peak torque.

CONCLUSION

The proportion of response was generally high after supplementation (82.9%-95.3%); however, a few participants did not benefit from the treatment. This underlines the potential need for personalized nutritional interventions in an exercise physiology context.

Conventional methods to prescribe exercise intensity are ineffective for exhaustive interval training

PURPOSE

To compare methods of relative intensity prescription for their ability to normalise performance (i.e., time to exhaustion), physiological, and perceptual responses to high-intensity interval training (HIIT) between individuals.

METHODS

Sixteen male and two female cyclists (age: 38 ± 11 years, height: 177 ± 7 cm, body mass: 71.6 ± 7.9 kg, maximal oxygen uptake ([Formula: see text]O2max): 54.3 ± 8.9 ml·kg-1 min-1) initially undertook an incremental test to exhaustion, a 3 min all-out test, and a 20 min time-trial to determine prescription benchmarks. Then, four HIIT sessions (4 min on, 2 min off) were each performed to exhaustion at: the work rate associated with the gas exchange threshold ([Formula: see text]GET) plus 70% of the difference between [Formula: see text]GET and the work rate associated with [Formula: see text]O2max; 85% of the maximal work rate of the incremental test (85%[Formula: see text]max); 120% of the mean work rate of the 20 min time-trial (120%TT); and the work rate predicted to expend, in 4 min, 80% of the work capacity above critical power. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter-individual variability.

RESULTS

For all dependent variables, the magnitude of inter-individual variability was high, and confidence intervals overlapped substantially, indicating that the relative intensity normalisation methods were similarly poor. Inter-individual coefficients of variation for time to exhaustion varied from 44.2% (85%[Formula: see text]max) to 59.1% (120%TT), making it difficult to predict acute HIIT responses for an individual.

CONCLUSION

The present study suggests that the methods of intensity prescription investigated do not normalise acute responses to HIIT between individuals.

Exercise intensity domains determined by heart rate at the ventilatory thresholds in patients with cardiovascular disease: new insights and comparisons to cardiovascular rehabilitation prescription recommendations

Objectives

To compare the elicited exercise responses at ventilatory thresholds (VTs: VT1 and VT2) identified by cardiopulmonary exercise testing (CPET) in patients with cardiovascular disease (CVD) with the guideline-directed exercise intensity domains; to propose equations to predict heart rate (HR) at VTs; and to compare the accuracy of prescription methods.

Methods

A cross-sectional study was performed with 972 maximal treadmill CPET on patients with CVD. First, VTs were identified and compared with guideline-directed exercise intensity domains. Second, multivariate linear regression analyses were performed to generate prediction equations for HR at VTs. Finally, the accuracy of prescription methods was assessed by the mean absolute percentage error (MAPE).

Results

Significant dispersions of individual responses were found for VTs, with the same relative intensity of exercise corresponding to different guideline-directed exercise intensity domains. A mathematical error inherent to methods based on percentages of peak effort was identified, which may help to explain the dispersions. Tailored multivariable equations yielded r2 of 0.726 for VT1 and 0.901 for VT2. MAPE for the novel VT1 equation was 6.0%, lower than that for guideline-based prescription methods (9.5 to 23.8%). MAPE for the novel VT2 equation was 4.3%, lower than guideline-based methods (5.8%-19.3%).

Conclusion

The guideline-based exercise intensity domains for cardiovascular rehabilitation revealed inconsistencies and heterogeneity, which limits the currently used methods. New multivariable equations for patients with CVD were developed and demonstrated better accuracy, indicating that this methodology may be a valid alternative when CPET is unavailable.

Oxidative Stress and Performance after Training in Professional Soccer (European Football) Players

Vitamins, hormones, free radicals, and antioxidant substances significantly influence athletic performance. The aim of this study was to evaluate whether these biological mediators changed during the season and if this was associated with the rate of improvement in performance after training, assessed by means of a standardized test. Professional male soccer players took part in the study. Two evaluations were performed: the first in the pre-season period and the second at the mid-point of the official season, after about 6 months of intensive training and weekly matches. Blood levels of vitamins D, B12, and folic acid, testosterone and cortisol, free radicals, and antioxidant substances were measured. Two hours after breakfast, a Yo-Yo test was performed. The relationships between the biological mediators and the rate of improvement after training (i.e., the increase in meters run in the Yo-Yo test between the pre-season and mid-season periods) were evaluated by means of a linear mixed models analysis. Results: Eighty-two paired tests were performed. The athletes showed better performance after training, with an increase in the meters run of about 20%. No significant relationships between the vitamin and hormone values and the gain in the performance test were observed. Plasmatic levels of free radicals increased significantly, as did the blood antioxidant potential. An indirect relationship between oxidative stress and the improvement in performance was observed (free radicals β ± SE: = -0.33 ± 0.10; p-value = 0.001), with lower levels of oxidative stress being associated with higher levels of performance in the Yo-Yo test. Monitoring the measures of oxidative stress could be a useful additional tool for coaches in training and/or recovery programs tailored to each player.