Slow and Steady, or Hard and Fast? A Systematic Review and Meta-Analysis of Studies Comparing Body Composition Changes between Interval Training and Moderate Intensity Continuous Training

Effect of self-paced sprint interval training and low-volume HIIT on cardiorespiratory fitness: the role of heart rate and power output

Aim

The primary aim was to assess the efficacy of self-paced sprint interval training (SIT) with low-volume high-intensity interval training (LV-HIIT) when performed without encouragement on improving cardiorespiratory fitness (CRF). A secondary aim was to explore whether the effort exerted during protocols [power output (PO) and heart rate (HR)] influenced the change in CRF.

Methods

In a randomised cross-over design, 82 previously inactive adults (m/f: 26/56, 28 ± 10 years, BMI 25 ± 3 kg m-2) undertook 6-weeks of self-paced SIT (4-8 × 30 s with 120 s recovery) or LV-HIIT (6-10 × 1 min with 1 min recovery) separated by a 4-week washout period. Sessions were completed 3×/week using WattBikes, and a target of >80% HRmax was suggested during the intervals. Markers of cardio-metabolic health were assessed before and after each intervention.

Results

Training increased VO2peak (SIT +3.1 ± 0.4 mL kg-1 min-1, LV-HIIT +2.7 ± 1.2 mL kg-1 min-1, P < 0.001) and decreased body fat % (P = 0.002), aortic pulse wave velocity (P = 0.002) and glucose tolerance 120 min following an oral glucose tolerance test (P = 0.024), with no difference between protocols (P > 0.05). When grouping participants into tertiles based on HR and PO responses (n = 27), those achieving a low HR had similar changes in VO2peak compared to the high HR group in both interventions (P > 0.05). For LV-HIIT, participants in the highest tertile for peak PO had a greater change in VO2peak compared to all other participants (Low 1.8 ± 4.1 mL kg-1 min-1, Medium 1.9 ± 3.3 mL kg-1 min-1, High 4.3 ± 3.6 ml kg-1 min-1, P = 0.020).

Discussion

Six-weeks of self-paced SIT and LV-HIIT induce comparable improvements in CRF, body composition, arterial stiffness and glucose tolerance. Importantly, higher HR did not elicit superior changes in CRF, but PO achieved during LV-HIIT may influence improvements.

Characteristics of High-Intensity Interval Training Influence Anthropometrics, Glycemic Control, and Cardiorespiratory Fitness in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Exercise is a non-pharmacological intervention for type 2 diabetes mellitus (T2DM), including moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). Despite diverse exercise protocol variations, the impact of these variations in HIIT on T2DM anthropometrics, glycemic control, and cardiorespiratory fitness (CRF) remains unclear.

OBJECTIVE

The aim was to examine the influence of HIIT protocol characteristics on anthropometrics, glycemic control, and CRF in T2DM patients and compare it to control (without exercise) and MICT.

METHODS

This review is registered in PROSPERO (CRD42021281398) and follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search, employing "high-intensity interval training" and "diabetes mellitus" in PubMed and Web of Science databases, with a "randomized controlled trial" filter, spanned articles up to January 2023.

RESULTS

Of 190 records, 29 trials were included, categorized by HIIT interval duration, training volume, and intervention period. Long-duration, high-volume, and long-term HIIT yields superior outcomes compared to control conditions for body mass, waist circumference, fasting plasma glucose, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), glycosylated hemoglobin (%HbA1c), and CRF. The findings favored HIIT over MICT for body mass in long-duration, high-volume, and short-term intervals (mean difference [MD] - 3.45, - 3.13, and - 5.42, respectively, all p < 0.05) and for CRF in long and medium work intervals and high volume (MD 1.91, 2.55, and 2.43, respectively, all p < 0.05), as well as in medium and long-term intervention (MD 2.66 and 2.21, respectively, all p < 0.05). Regardless of specific HIIT characteristics, no differences were found in the HIIT versus MICT comparison for glycemic control.

CONCLUSIONS

Specific HIIT protocol characteristics influence changes in anthropometrics, glycemic control, and CRF compared to control groups. However, compared to MICT, only longer duration, higher volume, and short-term HIIT improved body mass, waist circumference, and CRF in individuals with T2DM.

A systematic review of physical activity and nutritional interventions for the management of normal weight and overweight obesity

AIMS

Normal Weight Obesity (NWO) and Overweight Obesity (OWO) are prevalent conditions, yet knowledge of management is limited. This review aims to assess the effectiveness of physical activity and nutritional interventions in the management of NWO and OWO (together defined as BMI <30 kg/m2 with raised body fat).

DATA SYNTHESIS

Clinical trials including any physical activity or nutritional interventions, published between 2012 and 2022, evaluating body fat change were selected. Seven trials met inclusion criteria, including one single arm intervention, and six RCTs. A high intensity interval training intervention (high risk of bias) had the largest effect on reducing percentage body fat (MD: -6.8%, SE: 0.06). High protein intake interventions were also found to be effective (MD: -2.8%, SE: 0.27, MD: -2.0%, SE: 0.05). These three interventions led to greater increases in fat free mass. Two energy restricted interventions resulted in the highest mean weight loss (MD: -3.10 kg, SD: 0.87 (intervention only), MD: -2.90 kg, SE: 0.06), but also loss of fat free mass, resulting in low reductions in percentage body fat (MD: -1.10%, SD: 0.57 (intervention only), MD: -0.8%, SE 0.30). There was considerable heterogeneity between studies.

CONCLUSIONS

There are physical activity and nutritional interventions that could be efficacious for the management of NWO and OWO. However, there was considerable heterogeneity between studies. The most promising nutritional intervention is high protein intake and the least is energy restriction (without increased protein intake). More high-quality trials are needed to evaluate interventions, and to determine the best tools to measure adiposity.

The influence of specific resistance training methodological prescription variables on strength development under hypoxic conditions: A systematic review and meta-analysis

A systematic review and meta-analysis were conducted focused on the impact of specific methodological prescription variables in resistance training (RT) programming on muscle strength under hypoxic conditions. Searches of Pubmed-Medline, Web of Science, Sport Discuss and the Cochrane Library compared the effect of RT on strength development under hypoxic (RTH) vs. normoxic (RTN) conditions through the 1-repetition maximum (1RM) test. Apart from the overall meta-analysis, several RT methodological prescription variables available in the included studies (set end point, total weekly training volume, type of exercise, region of the body measured or type of routine) were analysed. Thirteen studies met the inclusion criteria. The overall analyses showed trivial differences in 1RM favouring RTH over RTN (SMD = 0.18 [CI: 0.04; 0.31]; p = 0.030). Sub-analyses revealed that a RT programme of a non-full-body routine, including 9 or more sets per exercise/week of multi-joint exercises performed to non-failure, favoured RTH for enhancing 1RM (p < 0.10). In conclusion, the evidence ratified a trivial benefit of RTH over RTN for muscle strength gains after a RT period. However, the handling of specific RT methodological prescription variables can slightly improve strength development outcomes in hypoxia.

Efficacy of Interval Training in Improving Body Composition and Adiposity in Apparently Healthy Adults: An Umbrella Review with Meta-Analysis

BACKGROUND

Although the efficacy of interval training for improving body composition has been summarized in an increasing number of systematic reviews in recent years, discrepancies in review findings and conclusions have been observed.

OBJECTIVE

This study aims to synthesize the available evidence on the efficacy of interval training compared with moderate-intensity continuous training (MICT) and nonexercise control (CON) in reducing body adiposity in apparently healthy adults.

METHODS

An umbrella review with meta-analysis was performed. A systematic search was conducted in seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) up to October 2023. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) comparing interval training and MICT/CON were included. Literature selection, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers. Meta-analyses were performed using a random-effects model. Subgroup analyses were conducted based on the type of interval training [high-intensity interval training (HIIT) and sprint interval training (SIT)], intervention duration, body mass index, exercise modality, and volume of HIIT protocols.

RESULTS

Sixteen systematic reviews, including 79 RCTs and 2474 unique participants, met the inclusion criteria. Most systematic reviews had a critically low (n = 6) or low (n = 6) AMSTAR-2 score. Interval training demonstrated significantly greater reductions in total body fat percent (BF%) compared with MICT [weighted mean difference (WMD) of - 0.77%; 95% confidence interval (CI) - 1.12 to - 0.32%] and CON (WMD of - 1.50%; 95% CI - 2.40 to - 0.58%). Significant reductions in fat mass, visceral adipose tissue, subcutaneous abdominal fat, and android abdominal fat were also observed following interval training compared to CON. Subgroup analyses indicated that both HIIT and SIT resulted in superior BF% loss than MICT. These benefits appeared to be more prominent in individuals with overweight/obesity and longer duration interventions (≥ 12 weeks), as well as in protocols using cycling as a modality and low-volume HIIT (i.e., < 15 min of high-intensity exercise per session).

CONCLUSIONS

This novel umbrella review with large-scale meta-analysis provides an updated synthesis of evidence with implications for physical activity guideline recommendations. The findings support interval training as a viable exercise strategy for reducing adiposity in the general population.

The Association Between Malignant Otitis Externa and Diabetes Mellitus in Africa: A Systematic Review

Diabetes mellitus is one of the risk factors for malignant otitis externa. There are very few studies on the disease in Africa and there is a need to pool the prior studies to highlight the characteristics of the disease. The study type is a systematic review and the PRISMA guidelines were followed. Using the appropriate terms, relevant medical databases were systematically searched. Thirty-two studies met the eligibility criteria with a total sample size of 848, who were mainly elderly. Diabetes mellitus was present in 94% of the participants. Average duration of diabetes diagnosis in the participants was 12.4 years. The pooled HbA1c was 9.8%. The most common symptoms were otalgia (96.1%), otorrhoea (75.8%) and hearing loss (56.1%). Pseudomonas was the most common isolate (72%). Fluoroquinolones and the 3rd-generation cephalosporins were the preferred antibiotics. The pooled cure rate from antimicrobial usage was 76.2%. In addition to medications, 24.6% of the affected individuals required debridement. About 1.6% of the participants died from malignant otitis externa. Malignant otitis externa is associated with poorly controlled diabetes. Pseudomonas is the most common cause and a significant proportion gets cured with prolonged antibiotherapy.

Influence of Pokémon Go Playing Style on Physical Activity and Its Effect on Kinanthropometry Variables and Body Composition in Adolescents

BACKGROUND

Pokémon Go is a mobile app that offers both continuous and intermittent (gamified) gameplay, but no previous research in adolescents is known to have addressed changes in physical activity and body composition according to playing style. For this reason, the aims of the present investigation were (1) to establish the differences in the level of physical activity, and its influence on the kinanthropometric and body composition, of the adolescent population, considering their Pokémon Go playing style; and (2) to analyze whether the practice of previous physical activity has an influence on the effects of the use of Pokémon Go on the level of physical activity and changes in kinanthropometric and body composition variables.

METHODS

A total of 94 adolescents (50 males and 44 females; mean age: 13.66 [1.17] years-old; mean body mass index: 20.82 [4.03] kg/m2) whose physical activity level and body composition were measured, participated in the investigation. Two groups of adolescents completed a 10-week intervention using Pokémon Go continuously (n = 30) or intermittently (n = 31), while the control group (n = 33) did not use any after-school app. A one-way analysis of variance (ANOVA), a multivariate analysis of variance, and 2 repeated-measures ANOVA were performed to analyze the data.

RESULTS

Inactive adolescents in the continuous use group increased their physical activity between the pretest and posttest (P = .038), but this did not occur in the active group. Regarding body composition variables, the increase in body mass (P < .001) and body mass index (P = .006) in the control group was significantly higher than in the continuous use group of adolescents who were inactive, but not in the active group, while the decrease in fat mass (P < .001-.036) and sum of 3 skinfolds (P < .001-.003) was significantly higher in both Pokémon Go use groups as compared to the control group, regardless of the previous physical activity level.

CONCLUSIONS

The continuous style of play seems to be more effective in increasing physical activity in adolescents, but the changes in body composition and kinanthropometric variables occur similarly with continuous and intermittent gameplay. Therefore, the playful use of Pokémon Go can be used in educational and health fields to produce changes in body composition in this population.

What is the optimal type and dose of physical activity for colorectal cancer prevention?

Epidemiological evidence shows that higher levels of physical activity reduce the relative risk of colon cancer by up to 20%. To design optimal physical activity interventions for primary prevention, it is important to understand how the specific characteristics of physical activity (type, intensity, overall volume) influence the magnitude of colon cancer risk reduction. Improving our understanding of the underlying biological mechanisms will also help to manipulate physical activity characteristics to precisely target mechanisms of action and identify populations most likely to benefit. This review synthesizes the best available evidence to explore how the type and dose of physical activity moderate the protective effect of physical activity on colon cancer.

Diabetes Mellitus as a risk factor for stroke among Nigerians: A systematic review and meta-analysis

Background

Diabetes mellitus is one of the modifiable risk factors for stroke. Stroke is common in Nigeria, but there is a paucity of national data on the frequency of diabetes in stroke. This study aimed to estimate to what extent diabetes a risk factor for stroke in Nigeria.

Methods

The study design is a systematic review, and the PRISMA guidelines were strictly followed. African Journal Online (AJOL), PubMed, SCOPUS and Google Scholar were systematically searched. The Newcastle-Ottawa scale was used to assess the quality, heterogeneity was determined with the I² statistic, and the DerSimonian Laird random effect model was selected for the meta-analysis.

Results

The studies were distributed across different regions of the country. The total sample size was 9397. The weighted average age of the patients with stroke was 53.7 years. The attributable risk of diabetes in stroke, among Nigerian patients, was 0.20 (95% CI: 0.17-0.22; p < 0.0001). The attributable risk has been rising steadily since the advent of the new century, and it is relatively higher in southern Nigeria.

Conclusion

The attributable risk of diabetes in stroke, among Nigerian patients is high. This varies across the regions but it is rising progressively nationally.

Meta-analysis of variation in sport and exercise science: Examples of application within resistance training research

Meta-analysis has become commonplace within sport and exercise science for synthesising and summarising empirical studies. However, most research in the field focuses upon mean effects, particularly the effects of interventions to improve outcomes such as fitness or performance. It is thought that individual responses to interventions vary considerably. Hence, interest has increased in exploring precision or personalised exercise approaches. Not only is the mean often affected by interventions, but variation may also be impacted. Exploration of variation in studies such as randomised controlled trials (RCTs) can yield insight into interindividual heterogeneity in response to interventions and help determine generalisability of effects. Yet, larger samples sizes than those used for typical mean effects are required when probing variation. Thus, in a field with small samples such as sport and exercise science, exploration of variation through a meta-analytic framework is appealing. Despite the value of embracing and exploring variation alongside mean effects in sport and exercise science, it is rarely applied to research synthesis through meta-analysis. We introduce and evaluate different effect size calculations along with models for meta-analysis of variation using relatable examples from resistance training RCTs.

The Effect of Feedback on Resistance Training Performance and Adaptations: A Systematic Review and Meta-analysis

BACKGROUND

Augmented feedback is often used during resistance training to enhance acute physical performance and has shown promise as a method of improving chronic physical adaptation. However, there are inconsistencies in the scientific literature regarding the magnitude of the acute and chronic responses to feedback and the optimal method with which it is provided.

OBJECTIVE

This systematic review and meta-analysis aimed to (1) establish the evidence for the effects of feedback on acute resistance training performance and chronic training adaptations; (2) quantify the effects of feedback on acute kinematic outcomes and changes in physical adaptations; and (3) assess the effects of moderating factors on the influence of feedback during resistance training.

METHODS

Twenty studies were included in this systematic review and meta-analysis. This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four databases were searched, and studies were included if they were peer-reviewed investigations, written in English, and involved the provision of feedback during or following dynamic resistance exercise. Furthermore, studies must have evaluated either acute training performance or chronic physical adaptations. Risk of bias was assessed using a modified Downs and Black assessment tool. Multilevel meta-analyses were performed to quantify the effects of feedback on acute and chronic training outcomes.

RESULTS

Feedback enhanced acute kinetic and kinematic outputs, muscular endurance, motivation, competitiveness, and perceived effort, while greater improvements in speed, strength, jump performance, and technical competency were reported when feedback was provided chronically. Furthermore, greater frequencies of feedback (e.g., following every repetition) were found to be most beneficial for enhancing acute performance. Results demonstrated that feedback improves acute barbell velocities by approximately 8.4% (g = 0.63, 95% confidence interval [CI] 0.36-0.90). Moderator analysis revealed that both verbal (g = 0.47, 95% CI 0.22-0.71) and visual feedback (g = 1.11, 95% CI 0.61-1.61) were superior to no feedback, but visual feedback was superior to verbal feedback. For chronic outcomes, jump performance might have been positively influenced (g = 0.39, 95% CI - 0.20 to 0.99) and short sprint performance was likely enhanced (g = 0.47, 95% CI 0.10-0.84) to a greater extent when feedback is provided throughout a training cycle.

CONCLUSIONS

Feedback during resistance training can lead to enhanced acute performance within a training session and greater chronic adaptations. Studies included in our analysis demonstrated a positive influence of feedback, with all outcomes showing superior results than when no feedback is provided. For practitioners, it is recommended that high-frequency, visual feedback is consistently provided to individuals when they complete resistance training, and this may be particularly useful during periods of low motivation or when greater competitiveness is beneficial. Alternatively, researchers must be aware of the ergogenic effects of feedback on acute and chronic responses and ensure that feedback is standardised when investigating resistance training.

The effects of water-based exercise on body composition: A systematic review and meta-analysis

AIMS

This study aimed to investigate the effects of water-based exercise (WBE) on body composition.

METHODS

Trials published up to October 28, 2022 were searched using the PubMed, EMBASE, Web of Science, Cochrane, Scopus, and Ovid databases. Randomized controlled trials of healthy adults published in English, comparing WBE and control groups, were included. Other studies with different research designs and participants with medical diagnoses were excluded. The main outcome measures were body weight (BW), body fat mass (BFM), body fat percentage (BFP), lean mass (LM), and skeletal muscle mass (SMM).

RESULTS

Overall, 17,458 potential studies were identified. After a closer inspection, 79 full-length articles were considered for further screening. Finally, 20 studies, involving 565 participants, were included in the meta-analysis. The WBE was beneficial in reducing BW, BFM, and BFP and increasing LM and SMM. Subgroup analyses were conducted based on different exercise intensities and times per week. Moderate- or moderate-vigorous-intensity exercise helped improve body composition, while lower-intensity WBE or aquatic high-intensity interval training (HIIT) seemed less helpful. Training for <120 min/week was insufficient to improve body composition. Training for >120 min/week was associated with improvements in body composition.

CONCLUSIONS

Moderate- or moderate-vigorous-intensity WBE helps improve body composition. Adults are encouraged to exercise for >120 min/week.

Stroke and dyslipidaemia in Africa: a meta-analysis of case-control studies

INTRODUCTION

Stroke is an acute neurological disorder characterized by an abrupt reduction in blood flow to the brain, spinal cord, or retina. There is a complex relationship between stroke and dyslipidaemia. The objective of the study was to determine the likelihood of dyslipidaemia in African stroke patients.

METHODS AND RESULTS

This study is a systematic review and meta-analysis of case-control studies to determine the odds ratio of dyslipidaemia among stroke patients in Africa. It followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The sources of data included Google Scholar, PubMed, SCOPUS, African Journal Online (AJOL), Research Square, SciELO, and medRxiv databases. The case-control studies eligible were conducted in Africa. The meta-analysis was carried out with Meta XL version 5.3, using the random effect model.

RESULTS

Ten studies met the eligibility criteria and the total sample size was 9599. The odds ratio of dyslipidaemia in all stroke cases in Africa was 1.61 (95% CI: 1.28-2.03) while that of ischaemic stroke and haemorrhagic stroke are 1.27 (0.54-2.98) and 1.71 (1.43-2.05) respectively.

CONCLUSION

Although not particularly substantial, there is an association between dyslipidaemia and stroke in Africa.

Efficacy of resistance training in hypoxia on muscle hypertrophy and strength development: a systematic review with meta-analysis

A systematic review and meta-analysis was conducted to determine the effects of resistance training under hypoxic conditions (RTH) on muscle hypertrophy and strength development. Searches of PubMed-Medline, Web of Science, Sport Discus and the Cochrane Library were conducted comparing the effect of RTH versus normoxia (RTN) on muscle hypertrophy (cross sectional area (CSA), lean mass and muscle thickness) and strength development [1-repetition maximum (1RM)]. An overall meta-analysis and subanalyses of training load (low, moderate or high), inter-set rest interval (short, moderate or long) and severity of hypoxia (moderate or high) were conducted to explore the effects on RTH outcomes. Seventeen studies met inclusion criteria. The overall analyses showed similar improvements in CSA (SMD [CIs] = 0.17 [- 0.07; 0.42]) and 1RM (SMD = 0.13 [0.0; 0.27]) between RTH and RTN. Subanalyses indicated a medium effect on CSA for longer inter-set rest intervals and a small effect for moderate hypoxia and moderate loads favoring RTH. Moreover, a moderate effect for longer inter-set rest intervals and a trivial effect for severe hypoxia and moderate loads favoring RTH was found on 1RM. Evidence suggests that RTH employed with moderate loads (60-80% 1RM) and longer inter-set rest intervals (≥ 120 s) enhances muscle hypertrophy and strength compared to normoxia. The use of moderate hypoxia (14.3-16% FiO2) seems to be somewhat beneficial to hypertrophy but not strength. Further research is required with greater standardization of protocols to draw stronger conclusions on the topic.

Thyrotoxicosis in Africa: a systematic review and meta-analysis of the clinical presentation

Background

Thyrotoxicosis is a common endocrine disorder. The clinical presentation is variable, and it is often misdiagnosed or diagnosed late in Africa. This study was aimed at collating and analyzing the clinical characteristics of the disease across the continent so as to enhance correct and timely diagnosis.

Methods

The study is a systematic review with a meta-analysis. Studies, done in Africa, which documented the clinical features of thyrotoxicosis were selected. African Journal Online (AJOL), PubMed, SCOPUS and Google Scholar, Research Square, SciELO, and medRxiv were systematically searched using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The study quality was assessed using the Newcastle-Ottawa scale. Heterogeneity was determined using I2 statistic and Cochran’s Q test. LFK index and the symmetry of the Doi plot were used to assess publication bias.

Results

The eligible studies were 59 and the total sample size was 9592. The most common symptoms of thyrotoxicosis on the continent included palpitations (69%), weight loss (65%), heat intolerance (64%), tiredness (49%), increased appetite (49%), hyperhidrosis (48%), and insomnia (47%). The most common signs were thyromegaly (88%), tachycardia (67%), sweaty palms (54%), hand tremor (49%), and exophthalmos (49%). Atrial fibrillation, heart failure, and thyrotoxic heart disease were found in 9, 12, and 22% respectively. Other findings were hypertension (25%) and diabetes (9%).

Conclusion

Clinical presentation of thyrotoxicosis varies, and understanding these peculiarities would mitigate misdiagnosis and delayed diagnosis in Africa.

A systematic review and meta-analysis of the etiology and treatment patterns of thyrotoxicosis in Africa

INTRODUCTION

Thyrotoxicosis is one of the most common endocrine disorders seen in clinical practice. This study aims to determine the etiologies and treatment modalities of thyrotoxicosis in Africa.

AREAS COVERED

The study design is a systematic review with a meta-analysis. Medical databases and the gray literature were systematically searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies done in Africa on the etiology and treatment of thyrotoxicosis were selected.

EXPERT OPINION

In Africa, it is still believed that autoimmune diseases, generally, are not as common as what is seen in the western world. The frequency of Graves' disease is reportedly lower in Africa. The treatment of thyrotoxicosis depends on the cause. Therefore, it is of substantial importance to establish the etiology following the diagnosis of the clinical syndrome.

Six sessions of low-volume high-intensity interval exercise improves resting fat oxidation

It remains unclear whether a practical model of low-volume high-intensity interval exercise improves resting fat oxidation (FatOx) which is associated with metabolic health. We aimed to determine the effects of a short-term practical model of high-intensity interval training (HIIT) on resting FatOx in young, healthy males. Thirty healthy males were randomly assigned to either single (HIITsingle; n=13) or double HIIT (HIITdouble; n=17) group. The HIITsingle group trained once a day, 3 days/week for 2 weeks, whilst the HIITdouble group performed 6 sessions of high-intensity exercise over 5 days by exercising twice a day every second day. Both groups completed 6 high-intensity exercise sessions consisting of 10×60 s of cycling at peak power output, interspersed by 75 s cycling at 60 W. With 1% false discovery rate (FDR) significance threshold, resting respiratory exchange ratio similarly decreased in HIITsingle (pre=0.83±0.03 vs post=0.80±0.03) and HIITdouble group (pre=0.82±0.04 vs post=0.80±0.02) [(p=0.001; partial eta squared () =0.310, FDR-adjusted p value=0.005)]. Resting FatOx increased similarly in HIITsingle (pre=1.07±0.39 mg·kg-1 fat free mass (FFM)·min-1 vs post=1.44±0.36 mg·kg-1 FFM·min-1) and HIITdouble group (pre=1.35±0.45 mg·kg-1 FFM·min-1 vs post=1.52±0.29 mg·kg-1 FFM·min-1) [(p<0.001; =0.411, FDR-adjusted p value=0.005)]. Our results demonstrate that only six sessions of a practical model of low-volume high-intensity exercise improves resting FatOx in young, healthy males.

Effects of Abdominal Microcurrent in the Consumption and Proportion of Energy Substrates during Aerobic Exercise: A Pilot Study

Microcurrent therapy can increase lipolytic activity. However, it is unknown if the increased availability of lipids can influence the selection of energy substrates during a single session of aerobic exercise. We aimed to analyze the effect of microcurrent application to the abdominal region in the consumption of lipids and carbohydrates, and respiratory exchange ratio (RER) during a single session of moderate aerobic exercise in young adults. A pilot study was conducted in which participants were allocated to intervention (IG) or placebo (PG) groups. In both groups, 40 min of microcurrent application with two frequencies (25 and 10 Hz) followed by 50 min of moderate-intensity aerobic exercise (45−55% of heart rate reserve) on a cycloergometer were performed. The microcurrent application was performed without intensity in the PG. A portable gas analyzer (K4b2) was used during exercise in both groups. Thirty-eight participants (20.6 ± 1.8 years; 18 in IG and 20 in PG) were enrolled. There were no significant differences in the consumption of substrates or RER between the groups during exercise (p > 0.05). Microcurrent application seems to be insufficient to influence the consumption of energy substrates and RER during a single session of aerobic exercise in young adults.