Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study

Effects of 24-week Polarized Training vs. Threshold Training in Obese Male Adults

The combination of high volume of moderate-intensity continuous training with a low volume of high-intensity interval training improved body composition and physical capacities in individuals with obesity. However, polarized training (POL) has never been used in adult men with obesity. Thus, the purpose of this study was to investigate changes in body composition and physical capacities induced by a 24-week POL or threshold (THR) program in obese male adults. Twenty male patients (mean age 39.8±6.3 yrs; mean body mass index [BMI] 31.6±2.7 kg∙m-2) participated in this study (n: 10 POL, n: 10 THR). After 24-week, body mass (BM) and fat mass (FM) decreased by -3.20±3.10 kg (P<0.05) and -3.80±2.80 kg (P<0.05), respectively, similarly in both groups. Maximal oxygen uptake (  ̇VO2max) and   ̇VO2 at respiratory compensation point (RCP) increased in the POL group (+8.5±12.2 and+9.0±17.0%, P<0.05) and in the THR group (+4.24±8.64 and+4.0±6.70%, P<0.05), as well   ̇VO2 at gas exchange threshold (GET) increased similarly in both groups (+12.8±12.0%, P<0.05). POL and THR were equally effective in improving body composition and physical capacities in obese subjects. Future studies are needed to determine whether adherence to the training program can be improved by adding a running competition compared with a group without competition at the end of the training program.

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.

Relative aerobic load of walking in people with multiple sclerosis

OBJECTIVE

To examine the energy demand of walking relative to aerobic capacity in people with multiple sclerosis.

DESIGN

Cross-sectional cohort study.

PATIENTS

A total of 45 people with multiple sclerosis (32 females), median disease duration 15 years (interquartile range (IQR) 9; 20), median Expanded Disability Status Scale 4 (min-max range: 2.0; 6.0).

METHODS

Aerobic capacity, derived from a cardiopulmonary exercise test and gas exchange measurements, assessed during a 6-min overground walk test at comfortable speed, were analysed. The relative aerobic load of walking was determined as the energy demand of walking relative to oxygen uptake at peak and at the first ventilatory threshold. Healthy reference data were used for clinical inference.

RESULTS

People with multiple sclerosis walk at a mean relative aerobic load of 60.0% (standard deviation 12.8%) relative to peak aerobic capacity, and 89.1% (standard deviation 19.9%) relative to the first ventilatory threshold. Fourteen participants walked above the first ventilatory threshold (31%). Peak aerobic capacity was reduced in 45% of participants, and energy demands were increased in 52% of participants.

CONCLUSION

People with multiple sclerosis walk at a relative aerobic load close to their first ventilatory threshold. A high relative aerobic load can guide clinicians to improve aerobic capacity or reduce the energy demands of walking.

Omics-driven investigation of the biology underlying intrinsic submaximal working capacity and its trainability

Submaximal exercise capacity is an indicator of cardiorespiratory fitness with clinical and public health implications. Submaximal exercise capacity and its response to exercise programs are characterized by heritability levels of about 40%. Using physical working capacity (power output) at a heart rate of 150 beats/min (PWC150) as an indicator of submaximal exercise capacity in subjects of the HERITAGE Family Study, we have undertaken multi-omics and in silico explorations of the underlying biology of PWC150 and its response to 20 wk of endurance training. Our goal was to illuminate the biological processes and identify panels of genes associated with human variability in intrinsic PWC150 (iPWC150) and its trainability (dPWC150). Our bioinformatics approach was based on a combination of genome-wide association, skeletal muscle gene expression, and plasma proteomics and metabolomics experiments. Genes, proteins, and metabolites showing significant associations with iPWC150 or dPWC150 were further queried for the enrichment of biological pathways. We compared genotype-phenotype associations of emerging candidate genes with reported functional consequences of gene knockouts in mouse models. We investigated the associations between DNA variants and multiple muscle and cardiovascular phenotypes measured in HERITAGE subjects. Two panels of prioritized genes of biological relevance to iPWC150 (13 genes) and dPWC150 (6 genes) were identified, supporting the hypothesis that genes and pathways associated with iPWC150 are different from those underlying dPWC150. Finally, the functions of these genes and pathways suggested that human variation in submaximal exercise capacity is mainly driven by skeletal muscle morphology and metabolism and red blood cell oxygen-carrying capacity.NEW & NOTEWORTHY Multi-omics and in silico explorations of the genes and underlying biology of submaximal exercise capacity and its response to 20 wk of endurance training were undertaken. Prioritized genes were identified: 13 genes for variation in submaximal exercise capacity in the sedentary state and 5 genes for the response level to endurance training, with no overlap between them. Genes and pathways associated with submaximal exercise capacity in the sedentary state are different from those underlying trainability.

Ventilatory Threshold Related to V̇O 2 reserve, Heart Rate Reserve, and Rating of Perceived Exertion in a Large Varied Sample

PURPOSE

ACSM guidelines state that aerobic exercise intensity should be 30%/40% to 89% V̇O 2 reserve (V̇O 2 R) or heart rate reserve (HRR). Determining the proper intensity within this range is the "art" of exercise prescription, often relying on rating of perceived exertion (RPE) as the adjunctive intensity modulator. Current guidelines do not consider the use of ventilatory threshold (VT) due to the need for specialized equipment and methodological issues. The purpose of this investigation was to evaluate VT related to V̇O 2peak , V̇O 2 R, HRR, and RPE across the full spectrum of very low to very high V̇O 2peak values.

METHODS

Eight hundred and sixty-three records of exercise tests were retrospectively examined. Data were stratified for V̇O 2peak , activity level, age, test modality, and sex.

RESULTS

When stratified for V̇O 2peak , V̇O 2 at VT (V̇O 2 vt) had a lower mean value of ~14 mL·kg -1 ·min -1 in the lowest fit, rose gradually until median V̇O 2peak , and rose steeply thereafter. When graphed relative to V̇O 2peak , V̇O 2 vt as a percentage of V̇O 2 R (VT%V̇O 2 R) resembled a U-shaped curve, with a nadir ~43% V̇O 2 R at V̇O 2peak ~40 mL·kg -1 ·min -1 . Average VT%V̇O 2 R increased to ~75% in groups with the lowest or highest V̇O 2peak . There was a large variance in the value of VT at all V̇O 2peak levels. Mean RPE at VT was 12.5 ± 0.93, regardless of V̇O 2peak .

CONCLUSIONS

Given the relationship of VT as the transition from moderate- to higher-intensity exercise, these data may help the understanding of aerobic exercise prescription in persons across the spectrum of V̇O 2peak values.

Sequencing patterns of ventilatory indices in less trained adults

Submaximal ventilatory indices, i.e., point of optimal ventilatory efficiency (POE) and anaerobic threshold (AT), are valuable indicators to assess the metabolic and ventilatory response during cardiopulmonary exercise testing (CPET). The order in which the ventilatory indices occur (ventilatory indices sequencing pattern, VISP), may yield additional information for the interpretation of CPET results and for exercise intensity prescription. Therefore, we determined whether different VISP groups concerning POE and AT exist. Additionally, we analysed fat metabolism via the exercise intensity eliciting the highest fat oxidation rate (Fatmax) as a possible explanation for differences between VISP groups. 761 less trained adults (41-68 years) completed an incremental exercise test on a cycle ergometer until volitional exhaustion. The ventilatory indices were determined using automatic and visual detection methods, and Fatmax was determined using indirect calorimetry. Our study identified two VISP groups with a lower work rate at POE compared to AT in VISPPOE < AT but not in group VISPPOE = AT. Therefore, training prescription based on POE rather than AT would result in different exercise intensity recommendations in 66% of the study participants and consequently in unintended physiological adaptions. VISPPOE < AT participants were not different to VISPPOE = AT participants concerning VO2peak and Fatmax. However, participants exhibiting a difference in work rate (VISPPOE < AT) were characterized by a higher aerobic capacity at submaximal work rate compared to VISPPOE = AT. Thus, analysing VISP may help to gain new insights into the complex ventilatory and metabolic response to exercise. But a methodological framework still must be established.

Physical activity, cardiorespiratory fitness, and cardiovascular health: A clinical practice statement of the American Society for Preventive Cardiology Part II: Physical activity, cardiorespiratory fitness, minimum and goal intensities for exercise training, prescriptive methods, and special patient populations

The prescription of exercise for individuals with and without cardiovascular disease (CVD) should be scientifically-based yet adapted to the patient. This scientific statement reviews the clinical and physiologic basis for the prescription of exercise, with specific reference to the volume of physical activity (PA) and level of cardiorespiratory fitness (CRF) that confer significant and optimal cardioprotective benefits. Recommendations are provided regarding the appropriate intensity, frequency, and duration of training; the concept of MET-minutes per week; critical components of the exercise session (warm-up, conditioning phase, cool-down); methodologies for establishing the training intensity, including oxygen uptake reserve (V̇O2R), target heart rate derivation and rating perceived exertion; minimum and goal intensities for exercise training; and, types of training activities, including resistance training, adjunctive lifestyle PA, marathon/triathlon training, and high-intensity interval training. In addition, we discuss the rationale for and value of exercise training programs for patients with peripheral artery disease, diabetes mellitus, and heart failure.

The HERITAGE Family Study: A Review of the Effects of Exercise Training on Cardiometabolic Health, with Insights into Molecular Transducers

The aim of the HERITAGE Family Study was to investigate individual differences in response to a standardized endurance exercise program, the role of familial aggregation, and the genetics of response levels of cardiorespiratory fitness and cardiovascular disease and diabetes risk factors. Here we summarize the findings and their potential implications for cardiometabolic health and cardiorespiratory fitness. It begins with overviews of background and planning, recruitment, testing and exercise program protocol, quality control measures, and other relevant organizational issues. A summary of findings is then provided on cardiorespiratory fitness, exercise hemodynamics, insulin and glucose metabolism, lipid and lipoprotein profiles, adiposity and abdominal visceral fat, blood levels of steroids and other hormones, markers of oxidative stress, skeletal muscle morphology and metabolic indicators, and resting metabolic rate. These summaries document the extent of the individual differences in response to a standardized and fully monitored endurance exercise program and document the importance of familial aggregation and heritability level for exercise response traits. Findings from genomic markers, muscle gene expression studies, and proteomic and metabolomics explorations are reviewed, along with lessons learned from a bioinformatics-driven analysis pipeline. The new opportunities being pursued in integrative -omics and physiology have extended considerably the expected life of HERITAGE and are being discussed in relation to the original conceptual model of the study.

Biomarkers and genetic polymorphisms associated with maximal fat oxidation during physical exercise: implications for metabolic health and sports performance

The maximal fat oxidation rate (MFO) assessed during a graded exercise test is a remarkable physiological indicator associated with metabolic flexibility, body weight loss and endurance performance. The present review considers existing biomarkers related to MFO, highlighting the validity of maximal oxygen uptake and free fatty acid availability for predicting MFO in athletes and healthy individuals. Moreover, we emphasize the role of different key enzymes and structural proteins that regulate adipose tissue lipolysis (i.e., triacylglycerol lipase, hormone sensitive lipase, perilipin 1), fatty acid trafficking (i.e., fatty acid translocase cluster of differentiation 36) and skeletal muscle oxidative capacity (i.e., citrate synthase and mitochondrial respiratory chain complexes II-V) on MFO variation. Likewise, we discuss the association of MFO with different polymorphism on the ACE, ADRB3, AR and CD36 genes, identifying prospective studies that will help to elucidate the mechanisms behind such associations. In addition, we highlight existing evidence that contradict the paradigm of a higher MFO in women due to ovarian hormones activity and highlight current gaps regarding endocrine function and MFO relationship.

Changes in the Second Ventilatory Threshold Following Individualised versus Standardised Exercise Prescription among Physically Inactive Adults: A Randomised Trial

The second ventilatory threshold (VT2) is established as an important indicator of exercise intensity tolerance. A higher VT2 allows for greater duration of higher intensity exercise participation and subsequently greater reductions in cardiovascular disease (CVD) risk. This study aimed to compare the efficacy of standardised and individualised exercise prescription on VT2 among physically inactive adults. Forty-nine physically inactive male and female participants (48.6 ± 11.5 years) were recruited and randomised into a 12-week standardised (n = 25) or individualised (n = 24) exercise prescription intervention. The exercise intensity for the standardised and individualised groups was prescribed as a percentage of heart rate reserve (HRR) or relative to the first ventilatory threshold (VT1) and VT2, respectively. Participants were required to complete a maximal graded exercise test at pre-and post-intervention to determine VT1 and VT2. Participants were categorised as responders to the intervention if an absolute VT2 change of at least 1.9% was attained. Thirty-eight participants were included in the analysis. A significant difference in VT2 change was found between individualised (pre vs. post: 70.6% vs. 78.7% maximum oxygen uptake (VO2max)) and standardised (pre vs. post: 72.5% vs. 72.3% VO2max) exercise groups. Individualised exercise prescription was significantly more efficacious (p = 0.04) in eliciting a positive response in VT2 (15/19, 79%) when compared to the standardised exercise group (9/19, 47%). Individualised exercise prescription appears to be more efficacious than standardised exercise prescription in eliciting a positive VT2 change among physically inactive adults. Increasing VT2 allows for greater tolerance to higher exercise intensities and therefore greater cardiovascular health outcomes.

Biological and methodological factors affecting V ̇ O 2 max response variability to endurance training and the influence of exercise intensity prescription

NEW FINDINGS

What is the topic of this review? Biological and methodological factors associated with the variable changes in cardiorespiratory fitness in response to endurance training. What advances does it highlight? Several biological and methodological factors exist that each contribute, to a given extent, to response variability. Notably, prescribing exercise intensity relative to physiological thresholds reportedly increases cardiorespiratory fitness response rates compared to when prescribed relative to maximum physiological values. As threshold-based approaches elicit more homogeneous acute physiological responses among individuals, when repeated over time, these uniform responses may manifest as more homogeneous chronic adaptations thereby reducing response variability.

ABSTRACT

Changes in cardiorespiratory fitness (CRF) in response to endurance training (ET) exhibit large variations, possibly due to a multitude of biological and methodological factors. It is acknowledged that ∼20% of individuals may not achieve meaningful increases in CRF in response to ET. Genetics, the most potent biological contributor, has been shown to explain ∼50% of response variability, whilst age, sex and baseline CRF appear to explain a smaller proportion. Methodological factors represent the characteristics of the ET itself, including the type, volume and intensity of exercise, as well as the method used to prescribe and control exercise intensity. Notably, methodological factors are modifiable and, upon manipulation, alter response rates to ET, eliciting increases in CRF regardless of an individual's biological predisposition. Particularly, prescribing exercise intensity relative to a physiological threshold (e.g., ventilatory threshold) is shown to increase CRF response rates compared to when intensity is anchored relative to a maximum physiological value (e.g., maximum heart rate). It is, however, uncertain whether the increased response rates are primarily attributable to reduced response variability, greater mean changes in CRF or both. Future research is warranted to elucidate whether more homogeneous chronic adaptations manifest over time among individuals, as a result of exposure to more homogeneous exercise stimuli elicited by threshold-based practices.

Individualized Aerobic Exercise in Neuromuscular Diseases: A Pilot Study on the Feasibility and Preliminary Effectiveness to Improve Physical Fitness

OBJECTIVE

Clear guidelines to prescribe aerobic exercise in neuromuscular diseases (NMD) are lacking, which hampers effective application in neuromuscular rehabilitation. This pilot study evaluated the feasibility and preliminary effectiveness of an individualized aerobic exercise program according to a recently developed training guide (B-FIT) to improve physical fitness in individuals with NMD.

METHODS

Thirty-one individuals who were ambulatory and had 15 different slowly progressive NMD participated in a 4-month, polarized, home-based, aerobic exercise program. The program included 2 low-intensity sessions and 1 high-intensity session per week. Feasibility outcomes were the following: completion rate, proportion of followed sessions, adverse events, and participant and therapist satisfaction based on a self-designed questionnaire. Submaximal incremental exercise tests were used to assess the effects on physical fitness.

RESULTS

Twenty-six participants (84%) completed the B-FIT program, and the proportion of followed sessions was >75%. Three adverse events were reported and resolved. Regarding satisfaction, participants (based on n = 9) reported feeling fitter, but training was considered insufficiently challenging. Physical therapists (n = 5) reported that B-FIT provides a clear, well-grounded guidance. They perceived the time investment for initiating the program and the carry-over to primary care as the main barriers. The mean (SD) submaximal heart rate (based on n = 20) reduced significantly by -6.5 beats per minute (95% CI = -11.8 to -1.2), from 121.7 (16.5) at baseline to 115.2 (14.3) after intervention. Submaximal ratings of perceived exertion, anaerobic threshold, and peak workload also improved significantly (P < .05).

CONCLUSION

The outcomes of this pilot study suggest that individualized aerobic exercise according to B-FIT is feasible and has potential to improve physical fitness in a wide variety of slowly progressive NMD. However, some barriers must be addressed before investigating the efficacy in a randomized controlled trial.

IMPACT

The outcomes of this study demonstrate the feasibility of individualized aerobic exercise according to the B-FIT training guide and the potential to improve physical fitness in NMD. Physical therapists indicated that the use of B-FIT provides a clear, well-grounded guidance. The training guide can support health care professionals in the application of aerobic exercise in adult neuromuscular rehabilitation.

LAY SUMMARY

Individualized exercise according to the B-FIT training guide is feasible in a wide variety of slowly progressive NMD and might help improve physical fitness.

Training for the HandbikeBattle: an explorative analysis of training load and handcycling physical capacity in recreationally active wheelchair users

PURPOSE

(1) to analyze training characteristics of recreationally active wheelchair users during handcycle training, and (2) to examine the associations between training load and change in physical capacity.

METHODS

Former rehabilitation patients (N = 60) with health conditions such as spinal cord injury or amputation were included. Participants trained for five months. A handcycling/arm crank graded exercise test was performed before and after the training period. Outcomes: peak power output per kg (POpeak/kg) and peak oxygen uptake per kg (VO₂peak/kg). Training load was defined as Training Impulse (TRIMP), which is rating of perceived exertion (sRPE) multiplied by duration of the session, in arbitrary units (AU). Training intensity distribution (TID) was also determined (time in zone 1, RPE ≤4; zone 2, RPE 5-6; zone 3, RPE ≥7).

RESULTS

Multilevel regression analyses showed that TRIMP_sRPE was not significantly associated with change in physical capacity. Time in zone 2 (RPE 5-6) was significantly associated with ΔVO₂peak, %ΔVO₂peak, ΔVO₂peak/kg and %ΔVO₂peak/kg.

CONCLUSION

Training at RPE 5-6 was the only determinant that was significantly associated with improvement in physical capacity. Additional controlled studies are necessary to demonstrate causality and gather more information about its usefulness, and optimal handcycle training regimes for recreationally active wheelchair users.IMPLICATIONS FOR REHABILITATIONMonitoring of handcycle training load is important to structure the training effort and intensity over time and to eventually optimize performance capacity. This is especially important for relatively untrained wheelchair users, who have a low physical capacity and a high risk of overuse injuries and shoulder pain.Training load can be easily calculated by multiplying the intensity of the training (RPE 0-10) with the duration of the training in minutes.Results on handcycle training at RPE 5-6 intensity in recreationally active wheelchair users suggests to be promising and should be further investigated with controlled studies.

Physical activity level and perceived exertion predict in-task affective valence to low-volume high-intensity interval exercise in adult males

Previous results reveal a decline in affective valence in response to progressive exercise in adults. However, this similar decline is not universally observed in response to high intensity interval exercise (HIIE), which may be due to its intermittent nature. The aim of the current study was to examine potential predictors of the in-task affective valence to low-volume HIIE (LV-HIIE; 10 × 60 s high-intensity intervals at 90% of maximal treadmill velocity interspersed by 60 s at 30% of maximal treadmill velocity). We analyzed data from 76 males (age and body mass index = 26.5 ± 4.4 yr and 27.3 ± 5.4 kg/m²) who had participated in previous investigations in our lab. Throughout each session, affective valence (Feeling Scale; + 5 to -5), rating of perceived exertion (RPE; Borg scale 6 to 20), and heart rate (HR) were measured. The predictors of in-task affective valence were analyzed during different phases of the LV-HIIE session (i.e. beginning, average of high-intensity intervals 1-3; middle, average of high-intensity intervals 4-7; and end, average of high-intensity intervals 8-10). Results showed a significant decline in affective valence (p < 0.001), increase in RPE (p < 0.001) and HR (p < 0.001) in response to LV-HIIE. Primary predictors of in-task affective valence to LV-HIIE were physical activity level and RPE (beginning, R² = 0.511, p < 0.001; middle, R² = 0.681, p < 0.001; end, R² = 0.742, p = 0.008). In conclusion, physical activity level and perceived exertion significantly predict the in-task affective valence to LV-HIIE in adult males.

Quantifying the effects of four weeks of low-volume high-intensity sprint interval training on V̇O2max through assessment of hemodynamics

BACKGROUND

Sprint interval training is a popular workout modality. Studies have eluded to a positive effect on maximal oxygen uptake, however little is known about the mechanistic basis of this adaptation. Therefore, the purpose of this study was to determine the effects of a short-term high-intensity sprint interval training (SIT) intervention on V̇O2max through quantification of both the respiratory and hemodynamic responses.

METHODS

Thirty-six physically active participants undertook 4 weeks of either cycling-based SIT (8×20 s at 170% P-V̇O2max with 10 s recovery) or continuous exercise training (CET) (30 min at 70% P-V̇O2max) 3 times per week. V̇O2max, blood-based markers and hemodynamic responses were assessed pre and post the intervention period. V̇O2max was assessed using breath-by-breath open circuit spirometry, while hemodynamic responses were monitored using thoracic impedance cardiography.

RESULTS

V̇O2max exhibited a non-significant 4.1% increase (ES=0.24) for SIT with 7.0% P=0.007 (ES=0.40) increase for CET. Hemodynamic responses (maximal cardiac output, maximal stroke volume) displayed non-significant responses for CET and SIT while a-vO2dif-max increased from 15.8±4.8 to 18.3±2.9 mL/100 mL) (P=0.02) (ES=0.63) in SIT.

CONCLUSIONS

V̇O2max is a function of maximal cardiac output and a-vO2dif-max, so for a meaningful change to occur in cardiorespiratory fitness, there must be a concomitant increase in O2 delivery. This study demonstrates that a low volume SIT intervention evokes peripherally mediated responses (a-vO2dif) and anaerobic substrate utilization rather than O2 delivery components. Future works should address the time course of the responses and when assessing V̇O2max-based responses that due attention be given to the hemodynamic responses as means of quantification of the response.

Time Course Changes in Confirmed 'True' VO 2 max After Individualized and Standardized Training

This study sought to examine time course changes in maximal oxygen consumption (VO ₂ max) confirmed with verification testing following 12 weeks of standardized vs. individualized exercise training. Participants (N=39) were randomly allocated to differing exercise intensity prescription groups: ventilatory threshold (individualized) or % heart rate reserve (standardized). At baseline, 4, 8, and 12 weeks, participants completed maximal exercise testing with a verification protocol to confirm ‘true VO ₂ max.’ VO ₂ max in the standardized group changed from 24.3±4.6 ml·kg ⁻¹ ·min ⁻¹ at baseline to 24.7±4.6, 25.9±4.7, and 26.0±4.2 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively, with a significant difference (p<0.05) in VO ₂ max at week 8 and 12 compared to baseline. The individualized group had increases in VO ₂ max from _{online 2} 9.5±7.5 ml·kg ⁻¹ ·min ⁻¹ at baseline to 30.6±8.4, 31.4±8.4, and 32.8±8.6 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively. In the individualized group, there were significant differences (p<0.05) in VO ₂ max from baseline to week 8 and 12 and a significant increase in VO ₂ max from week 8 to 1 _{online 2} . Although not statistically significant, our preliminary data demonstrates a more rapid and potent improvement in VO ₂ max when exercise intensity is individualized. This is the first investigation to employ use of the verification procedure to confirm ‘true VO ₂ max’ changes following exercise training using ventilatory thresholds.

Exercise Testing of Adolescents and Young Adults With Sickle Cell Disease: Perceptual Responses and the Gas Exchange Threshold

For individuals with sickle cell disease (SCD), mild to moderate exercise is advised, but self-regulation of these intensities is difficult. To regulate intensity, one SCD recommendation is to stop exercising at the first perception of fatigue. However, perceived effort and affect (how one feels) are perceptual cues that are commonly used to guide exercise intensity. This study (a) examined perceived effort, affect, and fatigue in relation to metabolic state (gas exchange) in adolescents and young adults (AYAs) with SCD, (b) explored guidelines AYAs use to self-regulate exercise, and (c) compared perceived effort and affect at gas exchange threshold (GET) with healthy counterparts. Twenty-two AYAs with SCD completed an incremental cycle test. Perceived effort, affect, and fatigue were assessed every 2 minutes. A mixed-effects linear model was conducted to model changes in effort, affect, and fatigue across time. Mean scores of effort and affect at GET were compared with published data of healthy counterparts. Participants were queried about self-regulation exercise strategies. Findings indicated that both perceived fatigue and effort at GET was lower than expected. Perceived effort was lower (p < .0001), and perceived affect was significantly higher (p = .0009) than healthy counterparts. Interviews revealed that most participants (95%) do not stop exercising until fatigue is moderate to severe, and many (73%) do not stop until symptoms are severe (chest tightness, blurry vision). Nurses should review guidelines for safe exercise with AYAs with SCD. Exercise training may be beneficial to AYAs with SCD for learning how to interpret bodily responses to exercise to improve self-regulation.

Noninvasive prediction of Blood Lactate through a machine learning-based approach

We hypothesized that blood lactate concentration([Lac]_blood) is a function of cardiopulmonary variables, exercise intensity and some anthropometric elements during aerobic exercise. This investigation aimed to establish a mathematical model to estimate [Lac]_blood noninvasively during constant work rate (CWR) exercise of various intensities. 31 healthy participants were recruited and each underwent 4 cardiopulmonary exercise tests: one incremental and three CWR tests (low: 35% of peak work rate for 15 min, moderate: 60% 10 min and high: 90% 4 min). At the end of each CWR test, venous blood was sampled to determine [Lac]_blood. 31 trios of CWR tests were employed to construct the mathematical model, which utilized exponential regression combined with Taylor expansion. Good fitting was achieved when the conditions of low and moderate intensity were put in one model; high-intensity in another. Standard deviation of fitting error in the former condition is 0.52; in the latter is 1.82 mmol/liter. Weighting analysis demonstrated that, besides heart rate, respiratory variables are required in the estimation of [Lac]_blood in the model of low/moderate intensity. In conclusion, by measuring noninvasive cardio-respiratory parameters, [Lac]_blood during CWR exercise can be determined with good accuracy. This should have application in endurance training and future exercise industry.

Training intensity relative to ventilatory thresholds determines cardiorespiratory fitness improvements in sedentary adults with obesity

The aim of the present study was to study if training intensity relative to ventilatory thresholds (VTs) determines the improvements in cardiorespiratory fitness (CRF) in middle-aged sedentary individuals with obesity. Before and after 16-weeks of HIIT (43-min alternating bouts at 70/90% of HR_MAX), oxygen consumption ( V˙ O₂) and heart rate (HR) at ventilatory threshold 1 ( V˙ O_2VT1, HR_VT1), ventilatory threshold 2 ( V˙ O_2VT2, HR_VT2) and at maximal effort ( V˙ O_2MAX, HR_MAX) were assessed during a graded cycle-ergometer exercise test. Retrospectively, participants were divided into two groups based on whether training intensities were under (UNDER; n = 39) or over (OVER; n = 37) VT₁ and VT₂. At baseline, age, body composition, V˙ O_2VT1, V˙ O_2VT2, and HR_MAX were similar in both groups. However, V˙ O_2MAX was higher in OVER (P = 0.033), whereas HR_VT1 and HR_VT2 were higher in UNDER (P < 0.05). V˙ O_2MAX (9.0%) and HR_MAX (2.2%) improved similarly in both groups. V˙ O_2VT1 and V˙ O_2VT2 improved with training in both groups (P < 0.001) but the improvement was larger in OVER versus UNDER in V˙ O_2VT1 (P = 0.013) and tended to be higher in V˙ O_2VT2 (P = 0.068). HR_VT1 increased only in OVER (P < 0.001), whereas HR_VT2 did not change in any group (P = 0.248). A 16-week programme of HIIT improves V˙ O_2MAX similarly in individuals training at intensities over or under their VTs. However, individuals training over their VTs showed a larger improvements in V˙ O_2VT1 expanding exercise workloads fuelled by oxidative metabolism.

Refuting the myth of non-response to exercise training: 'non-responders' do respond to higher dose of training

KEY POINTS

The prevalence of cardiorespiratory fitness (CRF) non-response gradually declines in healthy individuals exercising 60, 120, 180, 240 or 300 min per week for 6 weeks. Following a successive identical 6-week training period but comprising 120 min of additional exercise per week, CRF non-response is universally abolished. The magnitude of CRF improvement is primarily attributed to changes in haemoglobin mass. The potential for CRF improvement may be present and unveiled with appropriate exercise training stimuli in healthy individuals without exception.

ABSTRACT

One in five adults following physical activity guidelines are reported to not demonstrate any improvement in cardiorespiratory fitness (CRF). Herein, we sought to establish whether CRF non-response to exercise training is dose-dependent, using a between- and within-subject study design. Seventy-eight healthy adults were divided into five groups (1-5) respectively comprising one, two, three, four and five 60 min exercise sessions per week but otherwise following an identical 6-week endurance training (ET) programme. Non-response was defined as any change in CRF, determined by maximal incremental exercise power output (W_max ), within the typical error of measurement (±3.96%). Participants classified as non-responders after the ET intervention completed a successive 6-week ET period including two additional exercise sessions per week. Maximal oxygen consumption (V̇O2 max ), haematology and muscle biopsies were assessed prior to and after each ET period. After the first ET period, W_max increased (P < 0.05) in groups 2, 3, 4 and 5, but not 1. In groups 1, 2, 3, 4 and 5, 69%, 40%, 29%, 0% and 0% of individuals, respectively, were non-responders. After the second ET period, non-response was eliminated in all individuals. The change in V̇O2 max with exercise training independently determined W_max response (partial correlation coefficient, r_partial  ≥ 0.74, P < 0.001). In turn, total haemoglobin mass was the strongest independent determinant of V̇O2 max (r_partial  = 0.49, P < 0.001). In conclusion, individual CRF non-response to exercise training is abolished by increasing the dose of exercise and primarily a function of haematological adaptations in oxygen-carrying capacity.

The Effect of Short and Long Term Endurance Training on Systemic, and Muscle and Prefrontal Cortex Tissue Oxygen Utilisation in 40 - 60 Year Old Women

Purpose

Aerobic endurance training (ET) increases systemic and peripheral oxygen utilisation over time, the adaptation pattern not being linear. However, the timing and mechanisms of changes in oxygen utilisation, associated with training beyond one year are not known. This study tested the hypothesis that in women aged 40–60 years performing the same current training load; systemic O₂ utilisation (VO₂) and tissue deoxyhaemoglobin (HHb) in the Vastus Lateralis (VL) and Gastrocnemius (GAST) would be higher in long term trained (LTT; > 5 yr) compared to a short term trained (STT; 6–24 months) participants during ramp incremental (RI) cycling, but similar during square-wave constant load (SWCL) cycling performed at the same relative intensity (below ventilatory turn point [VTP]); and that pre-frontal cortex (PFC) HHb would be similar between participant groups in both exercise conditions.

Methods

Thirteen STT and 13 LTT participants performed RI and SWCL conditions on separate days. VO₂, and VL, GAST, and PFC HHb were measured simultaneously.

Results

VO_2peak was higher in LTT compared to STT, and VO₂ was higher in LTT at each relative intensities of 25%, 80% and 90% of VTP in SWCL. HHb in the VL was significantly higher in LTT compared to STT at peak exercise (4.54 ± 3.82 vs 1.55 ± 2.33 μM), and at 25% (0.99 ± 1.43 vs 0.04 ± 0.96 μM), 80% (3.19 ± 2.93 vs 1.14 ± 1.82 μM) and 90% (4.62 ± 3.12 vs 2.07 ± 2.49 μM) of VTP in SWCL.

Conclusions

The additional (12.9 ± 9.3) years of ET in LTT, resulted in higher VO₂, and HHb in the VL at peak exercise, and sub—VTP exercise. These results indicate that in women 40–60 years old, systemic and muscle O₂ utilisation continues to improve with ET beyond two years.

Current considerations related to physiological differences between the sexes and physical employment standards

The use of physical employment standards (PES) has helped ensure that workers have the physical attributes necessary to complete their jobs in a safe and efficient manner. However, PES used in the selection processes have not always reflected the critical physical requirements of the job tasks. Women generally have smaller anthropometric stature than men, less muscle mass, and therefore less strength, power, and endurance, particularly in the upper body. Nonetheless, these attributes in themselves are not valid grounds for exclusion from employment in physically demanding occupations. Selection standards based upon size or strength, irrespective of the job requirements, have resulted in the barring of capable women from physically demanding jobs, claims of gender bias, and costly litigations. To ensure all individuals are provided with equal access to employment, accurate characterization of the critical physical requirements of the job is paramount. This paper summarizes the existing research related to disparities between the sexes that contribute to sex differences in job performance in physically demanding occupations including physical and legal factors. Strategies for mitigating these differences in the setting of PES and the meeting of minimum employment standards are discussed. Where available, injury rates for women and men in physically demanding occupations are presented and the etiology considered. Finally, areas for further research are identified.

The training intensity distribution among well-trained and elite endurance athletes

Researchers have retrospectively analyzed the training intensity distribution (TID) of nationally and internationally competitive athletes in different endurance disciplines to determine the optimal volume and intensity for maximal adaptation. The majority of studies present a “pyramidal” TID with a high proportion of high volume, low intensity training (HVLIT). Some world-class athletes appear to adopt a so-called “polarized” TID (i.e., significant % of HVLIT and high-intensity training) during certain phases of the season. However, emerging prospective randomized controlled studies have demonstrated superior responses of variables related to endurance when applying a polarized TID in well-trained and recreational individuals when compared with a TID that emphasizes HVLIT or threshold training. The aims of the present review are to: (1) summarize the main responses of retrospective and prospective studies exploring TID; (2) provide a systematic overview on TIDs during preparation, pre-competition, and competition phases in different endurance disciplines and performance levels; (3) address whether one TID has demonstrated greater efficacy than another; and (4) highlight research gaps in an effort to direct future scientific studies.

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

The response to an exercise intervention is often described in general terms, with the assumption that the group average represents a typical response for most individuals. In reality, however, it is more common for individuals to show a wide range of responses to an intervention rather than a similar response. This phenomenon of 'high responders' and 'low responders' following a standardized training intervention may provide helpful insights into mechanisms of training adaptation and methods of training prescription. Therefore, the aim of this review was to discuss factors associated with inter-individual variation in response to standardized, endurance-type training. It is well-known that genetic influences make an important contribution to individual variation in certain training responses. The association between genotype and training response has often been supported using heritability estimates; however, recent studies have been able to link variation in some training responses to specific single nucleotide polymorphisms. It would appear that hereditary influences are often expressed through hereditary influences on the pre-training phenotype, with some parameters showing a hereditary influence in the pre-training phenotype but not in the subsequent training response. In most cases, the pre-training phenotype appears to predict only a small amount of variation in the subsequent training response of that phenotype. However, the relationship between pre-training autonomic activity and subsequent maximal oxygen uptake response appears to show relatively stronger predictive potential. Individual variation in response to standardized training that cannot be explained by genetic influences may be related to the characteristics of the training program or lifestyle factors. Although standardized programs usually involve training prescribed by relative intensity and duration, some methods of relative exercise intensity prescription may be more successful in creating an equivalent homeostatic stress between individuals than other methods. Individual variation in the homeostatic stress associated with each training session would result in individuals experiencing a different exercise 'stimulus' and contribute to individual variation in the adaptive responses incurred over the course of the training program. Furthermore, recovery between the sessions of a standardized training program may vary amongst individuals due to factors such as training status, sleep, psychological stress, and habitual physical activity. If there is an imbalance between overall stress and recovery, some individuals may develop fatigue and even maladaptation, contributing to variation in pre-post training responses. There is some evidence that training response can be modulated by the timing and composition of dietary intake, and hence nutritional factors could also potentially contribute to individual variation in training responses. Finally, a certain amount of individual variation in responses may also be attributed to measurement error, a factor that should be accounted for wherever possible in future studies. In conclusion, there are several factors that could contribute to individual variation in response to standardized training. However, more studies are required to help clarify and quantify the role of these factors. Future studies addressing such topics may aid in the early prediction of high or low training responses and provide further insight into the mechanisms of training adaptation.

Heart-Rate Variability and Training-Intensity Distribution in Elite Rowers

Purpose:

Elite endurance athletes may train in a polarized fashion, such that their training-intensity distribution preserves autonomic balance. However, field data supporting this are limited.

Methods:

The authors examined the relationship between heart-rate variability and training-intensity distribution in 9 elite rowers during the 26-wk build-up to the 2012 Olympic Games (2 won gold and 2 won bronze medals). Weekly averaged log-transformed square root of the mean sum of the squared differences between R-R intervals (Ln rMSSD) was examined, with respect to changes in total training time (TTT) and training time below the first lactate threshold (>LT1), above the second lactate threshold (LT2), and between LT1 and LT2 (LT1–LT2).

Results:

After substantial increases in training time in a particular training zone or load, standardized changes in Ln rMSSD were +0.13 (unclear) for TTT, +0.20 (51% chance increase) for time >LT1, –0.02 (trivial) for time LT1–LT2, and –0.20 (53% chance decrease) for time >LT2. Correlations (±90% confidence limits) for Ln rMSSD were small vs TTT (r = .37 ± .80), moderate vs time >LT1 (r = .43 ± .10), unclear vs LT1–LT2 (r = .01 ± .17), and small vs >LT2 (r = –.22 ± .50).

Conclusion:

These data provide supportive rationale for the polarized model of training, showing that training phases with increased time spent at high intensity suppress parasympathetic activity, while low-intensity training preserves and increases it. As such, periodized low-intensity training may be beneficial for optimal training programming.

Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training

ENDURANCE ATHLETES INTEGRATE FOUR CONDITIONING CONCEPTS IN THEIR TRAINING PROGRAMS: high-volume training (HVT), "threshold-training" (THR), high-intensity interval training (HIIT) and a combination of these aforementioned concepts known as polarized training (POL). The purpose of this study was to explore which of these four training concepts provides the greatest response on key components of endurance performance in well-trained endurance athletes.

METHODS

Forty eight runners, cyclists, triathletes, and cross-country skiers (peak oxygen uptake: (VO2peak): 62.6 ± 7.1 mL·min(-1)·kg(-1)) were randomly assigned to one of four groups performing over 9 weeks. An incremental test, work economy and a VO2peak tests were performed. Training intensity was heart rate controlled.

RESULTS

POL demonstrated the greatest increase in VO2peak (+6.8 ml·min·kg(-1) or 11.7%, P < 0.001), time to exhaustion during the ramp protocol (+17.4%, P < 0.001) and peak velocity/power (+5.1%, P < 0.01). Velocity/power at 4 mmol·L(-1) increased after POL (+8.1%, P < 0.01) and HIIT (+5.6%, P < 0.05). No differences in pre- to post-changes of work economy were found between the groups. Body mass was reduced by 3.7% (P < 0.001) following HIIT, with no changes in the other groups. With the exception of slight improvements in work economy in THR, both HVT and THR had no further effects on measured variables of endurance performance (P > 0.05).

CONCLUSION

POL resulted in the greatest improvements in most key variables of endurance performance in well-trained endurance athletes. THR or HVT did not lead to further improvements in performance related variables.

Effect of an 8-weeks aerobic training program in elderly on oxidative stress and HSP72 expression in leukocytes during antioxidant supplementation

OBJECTIVE

To investigate the effect of aerobic training in the context of antioxidant supplementation on systemic oxidative stress and leukocytes heat shock protein (Hsp)72 expression in the elderly.

DESIGN

Sixteen septuagenarians (8 males and 8 females, mean age 74.6) were supplemented with Vitamin C and E (respectively 500 and 100mg per day) and randomly assigned either to sedentary (AS) or individualized aerobically trained (AT) group for 8 weeks.

METHODS

Plasma Vitamin C and E concentrations and aerobic fitness, as well as resting and post graded exercise (GXT) Hsp72 expression in leukocytes, plasma levels of thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein product (AOPP) were measured pre and post training / supplementation.

RESULTS

At the end of the intervention, the two groups showed a significant increase in resting plasma vitamin C and E (approximately 50 and 20% increase respectively) and a significant decrease in both resting and post GXT plasma TBARS and AOPP (approximately 25 and 20% decrease respectively). These changes were of similar magnitude in the two groups. The reduced oxidative stress was concomitant with a 15% decreased expression of Hsp72 in monocytes and granulocytes in both groups.

CONCLUSION

This study provides evidence that in elderly, increased concentration of antioxidant vitamins C and E is associated with a reduction in oxidative stress and leukocytes Hsp72. In this context, 8 weeks of aerobic training has no impact on oxidative stress or leukocytes Hsp72 expression in elderly people.

Inter-individual variability in adaptation of the leg muscles following a standardised endurance training programme in young women

There is considerable inter-individual variability in adaptations to endurance training. We hypothesised that those individuals with a low local leg-muscle peak aerobic capacity (VO2peak) relative to their whole-body maximal aerobic capacity (VO2max) would experience greater muscle training adaptations compared to those with a relatively high VO2peak. 53 untrained young women completed one-leg cycling to measure VO2peak and two-leg cycling to measure VO2max. The one-leg VO2peak was expressed as a ratio of the two-leg VO2max (Ratio(1:2)). Magnetic resonance imaging was used to indicate quadriceps muscle volume. Measurements were taken before and after completion of 6 weeks of supervised endurance training. There was large inter-individual variability in the pre-training Ratio(1:2) and large variability in the magnitude of training adaptations. The pre-training Ratio(1:2) was not related to training-induced changes in VO2max (P = 0.441) but was inversely correlated with changes in one-leg VO2peak and muscle volume (P < 0.05). No relationship was found between the training-induced changes in two-leg VO2max and one-leg VO2peak (r = 0.21; P = 0.129). It is concluded that the local leg-muscle aerobic capacity and Ratio(1:2) vary from person to person and this influences the extent of muscle adaptations following standardised endurance training. These results help to explain why muscle adaptations vary between people and suggest that setting the training stimulus at a fixed percentage of VO2max might not be a good way to standardise the training stimulus to the leg muscles of different people.

Training methods and intensity distribution of young world-class rowers

PURPOSE

To describe the distribution of exercise types and rowing intensity in successful junior rowers and its relation to later senior success.

METHODS

36 young German male rowers (31 international, 5 national junior finalists; 19.2 +/- 1.4 y; 10.9 +/- 1.6 training sessions per week) reported the volumes of defined exercise and intensity categories in a diary over 37 wk. Training categories were analyzed as aggregates over the whole season and also broken down into defined training periods. Training organization was compared between juniors who attained national and international senior success 3 y later.

RESULTS

Total training time consisted of 52% rowing, 23% resistance exercise, 17% alternative training, and 8% warm-up programs. Based on heart rate control, 95% of total rowing was performed at intensities corresponding to <2 mmol x L(-1), 2% at 2 to 4 mmol x L(-1), and 3% at >4 mmol x L(-1) blood lactate. Low-intensity work remained widely unchanged at approximately 95% throughout the season. In the competition period, the athletes exhibited a shift within <2 mmol exercise toward lower intensity and within the remaining approximately 5% of total rowing toward more training near maximal oxygen consumption (VO(2max)) intensity. Retrospectively, among subjects going on to international success 3 y later had their training differed significantly from their peers only in slightly higher volumes at both margins of the intensity scope.

CONCLUSION

The young world-class rowers monitored here exhibit a constant emphasis on low-intensity steady-state rowing exercise, and a progressive polarization in the competition period. Possible mechanisms underlying a potential association between intensity polarization and later success require further investigation.

Physiological adaptations and analysis of training content in high school cross-country runners

The purposes of this study were to examine effects of a season of training on aerobic performance in cross-country distance runners and to analyze the training using subjective and objective techniques. Subjects averaged 184 minutes of running per week, with 45%, 24%, and 31% occurring in zones below, near, and above the heart rate (HR) corresponding to ventilatory threshold (VT(HR)), respectively (Zone 1: HR > 15 bpm below VT(HR); Zone 2: HR between Zone 1 and VT(HR); Zone 3: HR > VT(HR)). Maximal oxygen uptake (VO(2 max)) increased by 5.1%, 5-km race time by 46 seconds (3.7%), and 2-km time trial performance by 54 seconds (10.7%) from pre- to postseason. Results are similar to previous research demonstrating that short-term (< 3 months) endurance training elicits improvements in various physiological parameters. Findings were not consistent with previous research that suggests a discrepancy may exist between the runners' perceptions and the physiological effects of their training.

Autonomic recovery after exercise in trained athletes: intensity and duration effects

PURPOSE

To investigate the effects of training intensity and duration, through a range representative of training in endurance athletes, on acute recovery of autonomic nervous system (ANS) balance after exercise.

METHODS

Nine highly trained (HT) male runners (VO2max 72 +/- 5 mL.kg.min(-1), 14 +/- 3 training hours per week) and eight trained (T) male subjects (VO2max 60 +/- 5 mL.kg.min(-1), 7 +/- 1 training hours per week) completed preliminary testing to determine ventilatory thresholds (VT1, VT2) and VO2max. HT performed four intensity-controlled training sessions: 60 min and 120 min below VT1; 60 min with 30 min between VT1 and VT2 (threshold); and 60 min above VT2 (6 x 3 min at 96% VO2max, 2 min of recovery). T also completed the interval session to compare ANS recovery between HT and T. Supine heart rate variability (HRV) was quantified at regular intervals through 4 h of recovery.

RESULTS

When HT ran 60 or 120 min below VT1, HRV returned to pretraining values within 5-10 min. However, training at threshold (2.7 +/- 0.4 mM) or above VT2 (7.1 +/- 0.7 mM) induced a significant, but essentially identical, delay of HRV recovery (return to baseline by approximately 30 min). In T, HRV recovery was significantly slower, with HRV returning to baseline by >or=90 min after the same interval session.

CONCLUSIONS

In the highly trained endurance athlete, exercise for <or=120 min below the first ventilatory threshold causes minimal disturbance in ANS balance. ANS recovery is more rapid in highly trained than in trained subjects after high-intensity exercise. Further, the first ventilatory threshold may demarcate a "binary" threshold for ANS/HRV recovery in highly trained athletes, because further delays in HRV recovery with even higher training intensities were not observed.

Nine months aerobic fitness induced changes on blood lipids and lipoproteins in untrained subjects versus controls

Regular endurance exercise has favorable effects on cardiovascular risk factors. However, the impact of an exercise-induced change in aerobic fitness on blood lipids is often inconsistent. The purpose of this study was to investigate the effect of nine consecutive months of training on aerobic fitness and blood lipids in untrained adults. Thirty subjects 35-55 years of age (wt: 73.1 +/- 13.6 kg, height 171.1 +/- 9.0 cm, %body fat 24.6 +/- 6.3%, 14 males and 16 females) were randomly assigned to an exercise (EG) (N = 20) and control (CG) (N = 10) group. All subjects completed an incremental treadmill test, anthropometric measurements, and venous blood sample collection before and after the 9 months of exercise. Participants in the exercise group were supervised and adjusted for improvements in running performance, whereas no change was administered for the control group. One-way and multivariate ANOVA was conducted to determine significant differences in means for time and group in selected variables [body mass, % body fat, BMI; VO(2peak), km/h at 2.0 (v-LA2) and 4.0 (v-LA4) mmol l(-1) blood lactate (LA) concentration, km/h of the last load (v-max); TC, LDL-C, HDL-C, TG, Apo B, Apo A-1, and Lp (a)]. Correlation coefficients and multivariate regression analysis was used to determine the association between aerobic fitness and blood lipids. The exercise group improved significantly (P < 0.0001) in VO(2peak), v-LA2, v-LA4, v-max and exhibited a significant decrease in Apo B (P < 0.04) compared to the control group (NS). In 9 months, E achieved 24% increase in VO(2peak) and 18% reduction in Apo B, denoting the impact of cardiovascular fitness on cardiovascular risk.

Individualized exercise program for the treatment of severe fatigue in patients after allogeneic hematopoietic stem-cell transplant: a pilot study

Chronic cancer-related fatigue in otherwise asymptomatic post-allogeneic hematopoietic stem cell transplant (HSCT) patients is common and debilitating. This pilot study investigated whether patients with no clinical or psychological abnormalities but severe fatigue would respond to an individually adapted aerobic exercise program. Participants were 12 patients (eight male, and four female patients), median age 47 years and 41 months post-HSCT with a variety of hematopoietic cancer diagnoses. All underwent a 12-week individualized mild aerobic exercise program, preceded by a 4-week introduction and baseline testing phase. Psychological measures included fatigue, mood and depression. Exercise-related physiological outcomes included power output at ventilatory threshold 2 (VT2) and associated changes in stroke volume, heart rate, blood lactate concentration and ratings of perceived exertion. Patients were assessed for fatigue before, immediately after and at 3, 6, 9 and 12 months post-program. Significant improvements were found on both measures of fatigue (both P<0.001), with a very large effect size of 1.82 on the The Functional Assessment of Cancer Therapy - Fatigue Module, which were maintained over the follow-up period. Exercise testing revealed a mean increase (P<0.001) of 28% in power output at VT2 with an increase (P<0.001) in stroke volume and a decrease (P<0.001) in heart rate, blood lactate and perceived exertion at pre-intervention VT2 power output.

Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution?

This study was designed to quantify the daily distribution of training intensity in a group of well-trained junior cross-country skiers and compare the results of three different methods of training intensity quantification. Eleven male athletes performed treadmill tests to exhaustion to determine heart rate and VO2 corresponding to ventilatory thresholds (VT1, VT2), maximal oxygen consumption (VO2max), and maximal heart rate. VT1 and VT2 were used to delineate three intensity zones. During the same time period, all training sessions (N=384, 37 strength training, 347 endurance) performed over 32 consecutive days were quantified using continuous heart rate registration and session Rating of Perceived Exertion (RPE). In addition, a subset of 60 consecutive training sessions was quantified using blood lactate measurements. Intensity distribution across endurance training sessions (n=318) was similar when based on heart rate analysis (75+/-3%, zone 1; 8+/-3%, zone 2; 17+/-4%, zone 3) or session RPE (76+/-4%, zone 1; 6+/-5%, zone 2; 18+/-7%, zone 3). Similarly, from measurements of 60 consecutive sessions, 71% were performed with <or=2.0 mM blood lactate, 7% between 2 and 4 mM, and 22% with over 4 mM (mean=9.5+/-2.8 mM). In this group of nationally competitive junior skiers, training was organized after a polarized pattern, with most sessions performed clearly below (about 75%) or with substantial periods above (15-20%) the lactate accommodation zone, which is bounded by VT1 and VT2. The pattern quantified here is similar to that reported in observational studies of elite endurance athletes across several sports. It appears that elite endurance athletes train surprisingly little at the lactate threshold intensity.

Comparação entre limiar anaeróbio determinado por variáveis ventilatórias e pela resposta do lactato sanguíneo em ciclistas

Muitas investigações têm demonstrado que a coincidência entre os limiares ventilatórios e os limiares que se utilizam da resposta do lactato nem sempre ocorre, sugerindo que não existe relação entre causa e efeito entre os fenômenos. Dessa forma, o presente estudo teve como objetivos comparar e correlacionar os valores de consumo de oxigênio (VO2), potência (W) e freqüência cardíaca (FC) obtidos por protocolos de determinação do limiar ventilatório (LV) e limiar anaeróbio individual (IAT). A amostra foi constituída por oito ciclistas de níveis paulista e nacional (idade: 27,88 ± 8,77 anos; massa corporal: 65,19 ± 4,40kg; estatura: 169,31 ± 5,77cm). O IAT foi determinado iniciando-se com aquecimento de três minutos a 50W com aumentos progressivos de 50W.3min-1 até a exaustão voluntária, com as coletas de sangue aos 20 segundos finais de cada estágio e durante a recuperação. Para a determinação do LV, utilizou-se o mesmo protocolo adotado para a determinação do IAT, porém, sem efetuar as coletas de sangue. O LV foi identificado pelas mudanças da ventilação pulmonar e dos equivalentes ventilatórios de O2 e CO2. O teste t de Student não revelou diferenças estatisticamente significantes em nenhuma das variáveis obtidas. As associações encontradas foram altas e significativas. O VO2 (ml.kg-1.min-1), P (W) e FC (bpm) correspondente ao LV e IAT, e as associações entre as variáveis foram, respectivamente, de: 48,00 ± 3,82 vs 48,08 ± 3,71 (r = 0,90); 256,25 ± 32,04 vs 246,88 ± 33,91 (r = 0,84); 173,75 ± 9,18 vs 171,25 ± 12,02 (r = 0,97). De acordo com os resultados obtidos, pode-se concluir que o IAT e o LV produzem valores semelhantes de VO2, W e FC, o que favorece a adoção do LV por ser um método não-invasivo para determinação do limiar anaeróbio em ciclistas.

Training and performance characteristics among Norwegian international rowers 1970-2001

This study quantified changes in training volume, organization, and physical capacity among Norwegian rowers winning international medals between 1970 and 2001. Twenty-eight athletes were identified (27 alive). Results of physiological testing and performance history were available for all athletes. Twenty-one of 27 athletes responded to a detailed questionnaire regarding their training during their internationally competitive years. Maximal oxygen uptake (VO2 max) increased 12% (6.5+/- 0.4 vs. 5.8+/-0.2 L min(-1)) from the 1970s to the 1990s. Similarly, 6-min ergometer rowing performance increased almost 10%. Three major changes in training characteristics were identified: (1) training at a low blood lactate (< 2 mM) increased from 30 to 50 h month(-1) and race pace and supra-maximal intensity training (approximately 8-14 mM lactate) decreased from 23 to approximately 7 h month(-1); (2) training volume increased by approximately 20%, from 924 to 1128 h yr(-1); (3) altitude training was used as a pre-competition peaking strategy, but it is now integrated into the winter preparation program as periodic 2-3-week altitude camps. The training organization trends are consistent with data collected on athletes from other sports, suggesting a "polarized" pattern of training organization where a high volume of low intensity training is balanced against regular application of training bouts utilizing 90%-95% of VO2 max.