The Effect of Creatine Supplementation on Resistance Training-Based Changes to Body Composition: A Systematic Review and Meta-analysis.

ABSTRACT: Desai, I, Wewege, MA, Jones, MD, Clifford, BK, Pandit, A, Kaakoush, NO, Simar, D, and Hagstrom, AD. The effect of creatine supplementation on resistance training-based changes to body composition: A systematic review and meta-analysis. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this review was to determine the added effect of creatine supplementation on changes in body composition with resistance training in adults younger than 50 years. The review protocol was preregistered on the Open Science Framework (osf.io/x48a6/). Our primary outcome was lean body mass (LBM); secondary outcomes were body fat percentage (%) and body fat mass (kg). We performed a random-effects meta-analysis in R using the metafor package. Subgroup analyses were conducted to examine the effects of training status and use of a carbohydrate drink with creatine. We conducted a meta-regression to examine the moderating effect of total training volume. Statistical significance was set at p < 0.05. One thousand six hundred ninety-four records were screened, and 67 full-text articles were assessed for eligibility. Twelve studies were included in the meta-analysis. Fifty-two percentages of the studies had low risk, 41% some concerns, and 7% high risk of bias. Compared with resistance training (RT) alone, creatine supplementation increased LBM by 1.14 kg (95% CI 0.69 to 1.59), and reduced body fat percentage by -0.88% (95% CI -1.66 to -0.11) and body fat mass by -0.73 kg (95% CI -1.34 to -0.11). There were no differences between training status or carbohydrate subgroups. Training volume was not associated with effect size in all outcomes; 7 g or 0.3 g/kg of body mass of creatine per day is likely to increase LBM by 1 kg and reduce fat mass by 0.7 kg more than RT alone. Concurrent carbohydrate ingestion did not enhance the hypertrophy benefits of creatine.

If exercise is medicine, why don't we know the dose? An overview of systematic reviews assessing reporting quality of exercise interventions in health and disease.

OBJECTIVE: To determine how well exercise interventions are reported in trials in health and disease. DESIGN: Overview of systematic reviews. DATA SOURCES: PubMed, EMBASE, CINAHL, SPORTDiscus and PsycINFO from inception until June 2021. ELIGIBILITY CRITERIA: Reviews of any health condition were included if they primarily assessed quality of exercise intervention reporting using the Consensus on Exercise Reporting Template (CERT) or the Template for Intervention Description and Replication (TIDieR). We assessed review quality using a modified version of A MeaSurement Tool to Assess systematic Reviews. RESULTS: We identified 7804 studies and included 28 systematic reviews. The median (IQR) percentage of CERT and TIDieR items appropriately reported was 24% (19%) and 49% (33%), respectively. TIDieR items 1, Brief name (median=100%, IQR 4) and 2, Why (median=98%, IQR 6), as well as CERT item 4, Supervision and delivery (median=68%, IQR 89), were the best reported. For replication of exercise interventions, TIDieR item 8, When and how much, was moderately well reported (median=62%, IQR 68) although CERT item 8, Description of each exercise to enable replication (median=23%, IQR 44) and item 13, Detailed description of the exercise intervention (median=24%, IQR 66) were poorly reported. Quality of systematic reviews ranged from moderate to critically low quality. CONCLUSION: Exercise interventions are poorly reported across a range of health conditions. If exercise is medicine, then how it is prescribed and delivered is unclear, potentially limiting its translation from research to practice. PROSPERO REGISTRATION NUMBER: CRD42021261285; Open Science Framework: osf.io/my3ec/.

Cycling Power Outputs Predict Functional Threshold Power and Maximum Oxygen Uptake.

Denham, J, Scott-Hamilton, J, Hagstrom, AD, and Gray, AJ. Cycling power outputs predict functional threshold power and maximum oxygen uptake. J Strength Cond Res 34(12): 3489-3497, 2020-Functional threshold power (FTP) has emerged as a correlate of lactate threshold and is commonly assessed by recreational and professional cyclists for tailored exercise programing. To identify whether results from traditional aerobic and anaerobic cycling tests could predict FTP and V[Combining Dot Above]O2max, we analyzed the association between estimated FTP, maximum oxygen uptake (V[Combining Dot Above]O2max [ml·kg·min]) and power outputs obtained from a maximal cycle ergometry cardiopulmonary exercise test (CPET), and a 30-second Wingate test in a heterogeneous cohort of cycle-trained and untrained individuals (N = 40, mean ± SD; age: 32.6 ± 10.6 years; relative V[Combining Dot Above]O2max: 46.8 ± 9.1 ml·kg·min). The accuracy and sensitivity of the prediction equations were also assessed in young men (N = 11) before and after a 6-week sprint interval training intervention. Moderate-to-strong positive correlations were observed between FTP, relative V[Combining Dot Above]O2max, and power outputs achieved during incremental and 30-second Wingate cycling tests (r = 0.39-0.965, all p ≤ .05). Whilst maximum power achieved during incremental cycle testing (Pmax) and relative V[Combining Dot Above]O2max were predictors of FTP (r = 0.93), age and FTP (W·kg) estimated relative V[Combining Dot Above]O2max (r = 0.80). Our findings confirm that FTP predominantly relies on aerobic metabolism and indicate that both prediction models are sensitive enough to detect meaningful exercise-induced changes in FTP and V[Combining Dot Above]O2max. Thus, coaches should consider limiting the time and load demands placed on athletes by conducting a maximal cycle ergometry CPET to estimate FTP. In addition, a 20-minute FTP test is a convenient method to assess V[Combining Dot Above]O2max and is particularly relevant for exercise professionals without access to expensive CPET equipment.

Trained females exhibit less fatigability than trained males after a heavy knee extensor resistance exercise session.

PURPOSE: We examined differences between trained males and females in measures of muscular fatigability and central motor output after a resistance exercise session. METHODS: Sixteen trained males (n = 8) and females (n = 8) participated in the study. Knee extensor maximal torque and rate of torque development were measured before and after the exercise session, and the twitch interpolation technique was used during the maximal efforts to derive measures of voluntary activation and muscle contractility by supramaximal stimulation of the femoral nerve using 10 and 100 Hz doublets. Surface electromyograms were recorded during all maximal efforts to examine maximal and rate of quadriceps muscle activation. RESULTS: After exercise, maximal torque was reduced for both sexes by 26.3 ± 12.5% (p < 0.001). Absolute and relative vRTD was reduced only for males after exercise (p < 0.05). The early (0-50 ms) rate of muscle activation rise was similarly reduced for both sexes between 2.6 and 16.4% s-1 (p < 0.01), but males experienced an average decrease of 82.5 ± 72.1% s-1 for the maximal rate of muscle activation compared to no change for females (p = 0.02). Males had greater reductions (p < 0.05) for maximal twitch amplitudes and rate of twitch development (- 51.1 ± 21.5% and - 49.9 ± 22.8%, respectively) compared to females (- 35.8 ± 13.7% and - 31.5 ± 14.0%, respectively). CONCLUSIONS: These findings suggest that trained females are resistant to reductions in rapid torque development, despite similar reductions in maximal torque, after resistance exercise, with this result explained by better-maintained muscle contractility and maximal rate of muscle activation compared to males.

Changes in Unilateral Upper Limb Muscular Strength and Electromyographic Activity After a 16-Week Strength Training Intervention in Survivors of Breast Cancer.

Hagstrom, AD, Shorter, KA, and Marshall, PWM. Changes in unilateral upper limb muscular strength and Electroymographic activity after a 16-week strength training intervention in survivors of breast cancer. J Strength Cond Res 33(1): 225-233, 2019-Upper limb strength deficits are frequently observed following breast cancer (BC) and its treatments. It is currently unknown whether these unilateral deficits can be corrected by a standard bilateral strength training intervention. Twenty-three survivors of BC were included in this analysis. Fourteen performed a 16-week resistance training (RT) intervention, 9 were assigned to a usual care waitlist control group. Electromyographic analysis of the pectoralis major and triceps brachii were monitored during 3 maximal isometric contractions and a fatiguing endurance task. Muscular strength was significantly different between limbs at the start of the intervention (p = 0.02). Electromyographic amplitude and median frequency did not differ between limbs at the start of the intervention. Muscular strength was significantly different between limbs in the RT group at the end of the intervention (p = 0.01). Electromyographic amplitude did not differ between limbs or groups at the end of the intervention. Bilateral strength training did not correct the unilateral strength deficit observed in this group of survivors of breast cancer. Periods of unilateral strength training should be implemented into periodized RT programs in this cohort.

microRNAs in High and Low Responders to Resistance Training in Breast Cancer Survivors.

Accounting for one in three cancer diagnoses, breast cancer is the second most commonly diagnosed cancer in women. Exercise has a well-accepted role in the multi-disciplinary approach to rehabilitating breast cancer survivors. Despite the many known benefits of resistance training on women recovering from breast cancer, the molecular mechanisms are poorly understood. MicroRNAs are small non-coding RNAs that have crucial roles in growth and development. Here, we analysed the abundance of 9 miRNAs, with known roles in muscle physiology and some linked to cancer, in serum samples from 24 breast cancer survivors before and after a 16-week resistance training or usual care intervention. The resistance training group completed supervised thrice-weekly training. miRNA abundance was assessed before and after the intervention period using qPCR. There were no statistically significant changes in any of the miRNAs between groups after the intervention period (all p>0.05). After assessing miRNA abundance in context with high and low responders to resistance training, we observed that relative to low responders, high responders exhibited increased miR-133a-3p and a borderline statistically significant increase in miR-370-3p. Findings from our controlled study indicate the diverse interindividual miRNA responses to resistance training and reveal a discordant regulation between high and low responders.

Sprint Interval Training Decreases Circulating MicroRNAs Important for Muscle Development.

Small non-coding RNAs, such as microRNAs (miRNAs), have emerged as powerful post-transcriptional regulators of gene expression that play important roles in many developmental and biological processes. In this study, we assessed the abundance of circulating microRNAs important for skeletal muscle and heart adaptations to exercise (miR-1, miR-133a, miR-133b and miR-486), following acute exercise and short-term sprint interval training (SIT). Twenty-eight individuals completed four all-out efforts on a cycle ergometer, and donated blood before and 30 min after the cessation of exercise. A subset of 10 untrained men completed 4-6 efforts of SIT, three times a week for 6 weeks, and donated resting blood samples before and after the intervention. MiRNA TaqMan qPCR was performed and whilst no changes were observed after a single session of SIT (all p>0.05), the 6-wk SIT intervention significantly reduced the whole blood content of all four miRNAs (mean fold-changes: 0.37-0.48, all p<0.01). Our data suggests that circulating miRNAs are responsive to short-term SIT and could have roles in SIT-induced health and performance adaptations. Further work is required to establish whether circulating miRNAs could serve as biomarkers for predicting exercise training responses and monitoring exercise interventions.

The effect of resistance training on markers of immune function and inflammation in previously sedentary women recovering from breast cancer: a randomized controlled trial.

The purpose of this randomized controlled trial was to determine the effects of resistance training (RT) on markers of inflammation and immune function in breast cancer survivors. Thirty-nine breast cancer survivors were randomly assigned to a RT (n = 20) or control (n = 19) group. RT performed supervized exercise three times per week. Natural killer cell (NK) and natural killer T-cell (NKT) function, and markers of inflammation (serum TNF-α, IL-6, IL-10, and CRP) were measured before and after training. Changes in NK and NKT cell function were analyzed using ANCOVA, with the change score the dependent variable, and the baseline value of the same variable the covariate. Effect sizes (ES) were calculated via partial eta-squared. We found a significant reduction, and large associated ESs, in the RT group compared to the control group for change in NK cell expression of TNF-α (p = 0.005, ES = 0.21) and NKT cell expression of TNF-α (p = 0.04, ES = 0.12). No differences were observed in any serum marker. Significant improvements in all measurements of strength were found in RT compared to control (p < 0.001; large ESs ranging from 0.32 to 0.51). These data demonstrate that RT has a beneficial effect on the NK and NKT cell expression of TNF-α indicating that RT may be beneficial in improving the inflammatory profile in breast cancer survivors.

Are Exercise Interventions in Clinical Trials for Chronic Low Back Pain Dosed Appropriately to Meet the World Health Organization's Physical Activity Guidelines?

OBJECTIVE: This study aimed to estimate the proportion of exercise interventions tested in clinical trials of people with chronic low back pain (CLBP) that meet the World Health Organization's (WHO) physical activity guidelines. METHODS: A secondary analysis of the 2021 Cochrane review of exercise therapy for CLBP was performed. Data from each study were extracted by 1 reviewer and were checked by a second reviewer. Data extracted related to the frequency, duration and intensity of each exercise intervention, and the proportion of exercise interventions that met the WHO's physical activity guidelines (aerobic, muscle strengthening, or both) were determined. RESULTS: The 249 included trials comprised 426 exercise interventions. Few interventions reported an exercise type and dose consistent with the WHO guidelines (aerobic: 1.6%, muscle strengthening: 5.6%, both: 1.6%). Poor reporting of exercise intensity limited our ability to determine whether interventions met the guidelines. CONCLUSION: Few interventions tested in clinical trials for people with CLBP prescribe an exercise type and dose consistent with the WHO guidelines. Therefore, they do not appear sufficiently dosed to achieve broader health outcomes. Future trials should investigate the effect of WHO guideline-recommended exercise interventions on patient-reported outcomes (pain and disability) as well as health-related outcomes in people with CLBP. IMPACT: This exploratory analysis showed the lack of exercise interventions in the CLBP literature that meet the WHO's physical activity guidelines. With people in chronic pain groups, such as people with CLBP, being at higher risk for noncommunicable disease, it appears this is a key consideration for exercise practitioners when designing interventions for people with CLBP.

Data Informing Governing Body Resistance-Training Guidelines Exhibit Sex Bias: An Audit-Based Review.

The objective of this review was to examine the ratio of female and male participants utilised in data informing consensus statements and position stands in the field of resistance training (RT). In order to achieve this objective, we conducted an 'audit' style review. We accessed three databases: SPORTDiscus, MEDLINE and Google Scholar utilising the following search terms: resistance or strength training AND consensus statements or position statements/stands. Eligibility criteria included consensus statements and position stands for RT in youth, adults and older adults. In this paper we have used the term 'female' to describe biological sex. Gender is a social construct and often describes roles and behaviours that society assigns to men or women. In this paper we have used the term 'women' to describe gender. Reference lists from each guideline were screened with the number of male and female participants extracted from each study. We also extracted data on the gender of the authors of the statements. We located 11 guidelines encompassing a total of 104,251,363 participants. Youth guidelines were comprised of 69% male participants. There were 287 studies that included both sexes, 205 male-only and 92 female-only studies. Adult guidelines were comprised of 70% male participants. There were 104 studies that included both sexes, 240 male-only and 44 female-only studies. Older adult guidelines were comprised of 54% female participants. There were 395 studies that included both sexes, 112 male-only and 83 female-only studies. Women authors comprised 13% of all authors of position stands and consensus statements. These results demonstrate an under-representation of females and women as both participants and as authors. It is imperative to ensure that data informing governing body guidelines and consensus statements are representative of the population they aim to inform. If this is not possible, guidelines should clearly state when their data and recommendations are based primarily upon one sex.

Evaluating the effect of upper-body morbidity on quality of life following primary breast cancer treatment: a systematic review and meta-analysis.

PURPOSE: Improvements in breast cancer management continue to increase survival and life expectancy after treatment. Yet the adverse effects of treatment may persist long term, threatening physical, psychological, and social wellbeing, leading to impaired quality of life (QOL). Upper-body morbidity (UBM) such as pain, lymphoedema, restricted shoulder range of motion (ROM), and impaired function are widely reported after breast cancer treatment, but evidence demonstrating its impact on QOL is inconsistent. Therefore, the aim of the study was to conduct a systematic review and meta-analysis evaluating the effect of UBM on QOL following primary breast cancer treatment. METHODS: The study was prospectively registered on PROSPERO (CRD42020203445). CINAHL, Embase, Emcare, PsycInfo, PubMed/Medline, and SPORTDiscus databases were searched for studies reporting QOL in individuals with and without UBM following primary breast cancer treatment. Primary analysis determined the standardised mean difference (SMD) in physical, psychological, and social wellbeing scores between UBM + /UBM - groups. Secondary analyses identified differences in QOL scores between groups, according to questionnaire. RESULTS: Fifty-eight studies were included, with 39 conducive to meta-analysis. Types of UBM included pain, lymphoedema, restricted shoulder ROM, impaired upper-body function, and upper-body symptoms. UBM + groups reported poorer physical (SMD = - 0.99; 95%CI = - 1.26, - 0.71; p < 0.00001), psychological (SMD = - 0.43; 95%CI = - 0.60, - 0.27; p < 0.00001), and social wellbeing (SMD = - 0.62; 95%CI = - 0.83, - 0.40; p < 0.00001) than UBM - groups. Secondary analyses according to questionnaire showed that UBM + groups rated their QOL poorer or at equal to, UBM - groups across all domains. CONCLUSIONS: Findings demonstrate the significant, negative impact of UBM on QOL, pervading physical, psychological, and social domains. IMPLICATIONS FOR CANCER SURVIVORS: Efforts to assess and minimise the multidimensional impact of UBM are warranted to mitigate impaired QOL after breast cancer.

Comparative effectiveness and safety of analgesic medicines for adults with acute non-specific low back pain: systematic review and network meta-analysis.

OBJECTIVE: To evaluate the comparative effectiveness and safety of analgesic medicines for acute non-specific low back pain. DESIGN: Systematic review and network meta-analysis. DATA SOURCES: Medline, PubMed, Embase, CINAHL, CENTRAL, ClinicalTrials.gov, clinicialtrialsregister.eu, and World Health Organization's International Clinical Trials Registry Platform from database inception to 20 February 2022. ELIGIBILITY CRITERIA FOR STUDY SELECTION: Randomised controlled trials of analgesic medicines (eg, non-steroidal anti-inflammatory drugs, paracetamol, opioids, anti-convulsant drugs, skeletal muscle relaxants, or corticosteroids) compared with another analgesic medicine, placebo, or no treatment. Adults (≥18 years) who reported acute non-specific low back pain (for less than six weeks). DATA EXTRACTION AND SYNTHESIS: Primary outcomes were low back pain intensity (0-100 scale) at end of treatment and safety (number of participants who reported any adverse event during treatment). Secondary outcomes were low back specific function, serious adverse events, and discontinuation from treatment. Two reviewers independently identified studies, extracted data, and assessed risk of bias. A random effects network meta-analysis was done and confidence was evaluated by the Confidence in Network Meta-Analysis method. RESULTS: 98 randomised controlled trials (15 134 participants, 49% women) included 69 different medicines or combinations. Low or very low confidence was noted in evidence for reduced pain intensity after treatment with tolperisone (mean difference -26.1 (95% confidence intervals -34.0 to -18.2)), aceclofenac plus tizanidine (-26.1 (-38.5 to -13.6)), pregabalin (-24.7 (-34.6 to -14.7)), and 14 other medicines compared with placebo. Low or very low confidence was noted for no difference between the effects of several of these medicines. Increased adverse events had moderate to very low confidence with tramadol (risk ratio 2.6 (95% confidence interval 1.5 to 4.5)), paracetamol plus sustained release tramadol (2.4 (1.5 to 3.8)), baclofen (2.3 (1.5 to 3.4)), and paracetamol plus tramadol (2.1 (1.3 to 3.4)) compared with placebo. These medicines could increase the risk of adverse events compared with other medicines with moderate to low confidence. Moderate to low confidence was also noted for secondary outcomes and secondary analysis of medicine classes. CONCLUSIONS: The comparative effectiveness and safety of analgesic medicines for acute non-specific low back pain are uncertain. Until higher quality randomised controlled trials of head-to-head comparisons are published, clinicians and patients are recommended to take a cautious approach to manage acute non-specific low back pain with analgesic medicines. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019145257.

The Effect of Resistance Training in Healthy Adults on Body Fat Percentage, Fat Mass and Visceral Fat: A Systematic Review and Meta-Analysis.

BACKGROUND: Resistance training is the gold standard exercise mode for accrual of lean muscle mass, but the isolated effect of resistance training on body fat is unknown. OBJECTIVES: This systematic review and meta-analysis evaluated resistance training for body composition outcomes in healthy adults. Our primary outcome was body fat percentage; secondary outcomes were body fat mass and visceral fat. DESIGN: Systematic review with meta-analysis. DATA SOURCES: We searched five electronic databases up to January 2021. ELIGIBILITY CRITERIA: We included randomised trials that compared full-body resistance training for at least 4 weeks to no-exercise control in healthy adults. ANALYSIS: We assessed study quality with the TESTEX tool and conducted a random-effects meta-analysis, with a subgroup analysis based on measurement type (scan or non-scan) and sex (male or female), and a meta-regression for volume of resistance training and training components. RESULTS: From 11,981 records, we included 58 studies in the review, with 54 providing data for a meta-analysis. Mean study quality was 9/15 (range 6-15). Compared to the control, resistance training reduced body fat percentage by - 1.46% (95% confidence interval - 1.78 to - 1.14, p < 0.0001), body fat mass by - 0.55 kg (95% confidence interval - 0.75 to - 0.34, p < 0.0001) and visceral fat by a standardised mean difference of - 0.49 (95% confidence interval - 0.87 to - 0.11, p = 0.0114). Measurement type was a significant moderator in body fat percentage and body fat mass, but sex was not. Training volume and training components were not associated with effect size. Resistance training reduces body fat percentage, body fat mass and visceral fat in healthy adults. STUDY REGISTRATION: osf.io/hsk32.

Relationship between echocardiogram and physical parameters in experienced resistance trainers: a pilot study.

BACKGROUND: A paucity of research exists concerning physiological factors influencing heart structure and function in strength athletes. This pilot study investigated whether body composition and muscle performance are associated with indices of cardiac structure and function in experienced resistance trainers. METHODS: A cross-sectional study designed was employed to address the study aim. Seventeen males (median age 33.0 years) and eight females (median age 32.5 years) with backgrounds in bodybuilding and powerlifting participated in this study. Muscle performance, body composition and echocardiographic measures were performed. Mann-Whitney U-tests were used to examine differences between males and females. Spearman's Rho partial correlation analyses (adjusting for sex) were conducted to examine relationships between physical and echocardiogram parameters. RESULTS: Moderate to strong positive correlations were found between fat-free mass and aortic root, right ventricular internal dimension, interventricular septum thickness, left ventricular posterior wall thickness, left atrium area, left ventricular end-diastolic volume, and left ventricular end-systolic volume (r: 0.43-0.76, P≤0.03). Moderate to strong positive correlations were found between leg press 1RM and aortic root, left ventricular internal dimension diastole, left atrium area, left ventricular end-diastolic volume, and left ventricular end-systolic volume (r: 0.49-0.67, P≤0.02). CONCLUSIONS: Resistance trainers with greater fat-free mass and lower body strength appear to have larger cardiac structures. Changes in heart size and function are likely to result from long-term strenuous resistance training. Due to the suspected prevalence of performance enhancing drug use among powerlifters and bodybuilders, care is required to rule out pathological conditions.

Sex Differences in Adaptations in Muscle Strength and Size Following Resistance Training in Older Adults: A Systematic Review and Meta-analysis.

BACKGROUND: Reductions in muscle size and strength occur with aging. These changes can be mitigated by participation in resistance training. At present, it is unknown if sex contributes to differences in adaptation to resistance training in older adults. OBJECTIVE: The aim of this systematic review was to determine if sex differences are apparent in adaptations to resistance training in older adults. DESIGN: Systematic review with meta-analysis. DATA SOURCES: Web of Science; Science Direct; SPORTDiscus; CINAHL; and MEDLINE were searched from inception to June 2020. ELIGIBILITY CRITERIA: Studies where males and females older than 50 years of age performed identical resistance training interventions and had outcome measures of muscle strength or size. RESULTS: We initially screened 5337 studies. 30 studies (with 41 comparison groups) were included in our review (1410 participants; 651 males, 759 females). Mean study quality was 14.7/29 on a modified Downs and Black checklist, considered moderate quality. Females gained more relative lower-body strength than males (g = - 0.21 [95% CI - 0.33, - 0.10], p = 0.0003) but there were no differences in relative change for upper-body strength (g = - 0.29 [95% CI - 0.62, 0.04], p = 0.08) or relative muscle size (g = 0.10 [95% CI - 0.04, 0.23], p = 0.16). Males gained more absolute upper-body strength (g = 0.48 [95% CI 0.09, 0.88], p = 0.016), absolute lower-body strength (g = 0.33 [95% CI 0.19, 0.47], p < 0.0001), and absolute muscle size (g = 0.45 [95% CI 0.23, 0.66], p < 0.0001). CONCLUSION: Our results indicate that sex differences in adaptations to resistance training are apparent in older adults. However, it is evident that the interpretation of sex-dependent adaptations to resistance training is heavily influenced by the presentation of the results in either an absolute or relative context. STUDY REGISTRATION: Open Science Framework (osf.io/afn3y/).

Co-expression analysis identifies networks of miRNAs implicated in biological ageing and modulated by short-term interval training.

Exercise training seems to promote healthy biological ageing partly by inducing telomere maintenance, yet the molecular mechanisms are not fully understood. Recent studies have emphasised the importance of microRNAs (miRNAs) in ageing and their ability to mirror pathophysiological alterations associated with age-related diseases. We examined the association between aerobic fitness and leukocyte telomere length before determining the influence of vigorous exercise training on the regulation of leukocyte miRNA networks. Telomere length was positively correlated to aerobic fitness (r = 0.32, p = 0.02). 104 miRNAs were differentially expressed after six weeks of thrice-weekly sprint interval training (SIT) in healthy men (q < 0.05). Gene co-expression analysis (WGCNA) detected biologically meaningful miRNA networks, five of which were significantly correlated with pre-SIT and post-SIT expression profiles (p < 0.001) and telomere length. Enrichment analysis revealed that the immune response, T cell differentiation and lipid metabolism associated miRNAs clusters were significantly down-regulated after SIT. Using data acquired from the Gene Expression Omnibus (GEO), we also identified two co-expressed miRNAs families that were modulated by exercise training in previous investigations. Collectively, our findings highlight the miRNA networks implicated in exercise adaptations and telomere regulation, and suggest that SIT may attenuate biological ageing through the control of the let-7 and miR-320 miRNA families.

The Effect of Resistance Training on Body Composition During and After Cancer Treatment: A Systematic Review and Meta-Analysis.

BACKGROUND: Changes in body composition during cancer treatments have been linked with poorer outcomes, and increased morbidity and mortality. The effect of resistance training (RT) on body composition in cancer cohorts is debated. OBJECTIVE: We conducted a systematic review and meta-analysis to determine the effect of RT on body composition during and after treatment. METHODS: We searched five electronic databases for articles up to 1 February 2021 and included randomized controlled trials that compared RT with a non-exercise control in adults with cancer. Risk of bias was assessed using the RoB 2 tool. Pairwise, random-effects meta-analysis was used to synthesize the available data. RESULTS: Overall, we included 15 studies (n = 1368). After treatment (11 studies), RT increased lean mass with moderate heterogeneity {0.41 kg [95% confidence interval (CI) 0.05, 0.76], p = 0.029; I2 = 47.1%, p = 0.02} and decreased fat mass with substantial heterogeneity (- 0.59 kg [95% CI - 1.05, - 0.12], p = 0.019; I2 = 69.1%, p < 0.001). During treatment (4 studies), RT did not increase lean mass (0.71 kg [95% CI - 0.04, 1.45], p = 0.05; I2 = 0.0%, p = 0.75) or reduce fat mass (0.00 kg [95% CI - 5.31, 5.30], p = 0.99; I2 = 0.0%, p = 0.62), both with no heterogeneity. CONCLUSION: Modest improvements in body composition were observed following RT after cancer treatment; however, no changes were observed during treatment. These adaptations are markedly lower than those observed in healthy cohorts but may be clinically meaningful for the cancer survivorship population. At present it is unclear if these diminished adaptations are due to ineffective exercise prescriptions in cancer cohorts or due to an innate anabolic resistance as a result of cancer and its treatments. STUDY REGISTRATION: Open Science Framework (osf.io/x6z72).

The Effect of Resistance Training in Women on Dynamic Strength and Muscular Hypertrophy: A Systematic Review with Meta-analysis.

BACKGROUND: The effect of resistance training (RT) on adaptations in muscular strength and hypertrophy has never been examined in an exclusively female synthesis of the literature. OBJECTIVE: The objectives of this study were threefold: (1) to systematically review the literature on female adaptations to RT, characterising the effect in terms of muscular strength and hypertrophy; (2) to distinguish the individual effects of intervention duration, frequency, and intensity on these adaptations via sub-analysis; (3) to draw evidence-based conclusions regarding training expectations in female populations. METHODS: Three electronic databases were searched using terms related to RT combined with females or women. Random-effects meta-analyses were undertaken to estimate the effect of RT on muscular strength and hypertrophy in females. Possible predictors that may have influenced training-related effects (e.g., training intensity and volume) were explored using univariate analyses. RESULTS: The systematic search identified 14,067 articles of which a total of 24 studies met the inclusion criteria and were eligible. Upper body strength was assessed in 15 studies, lower body strength in 19 studies, and muscular hypertrophy in 15 studies. Study duration lasted between 4 weeks and 12 months. Large-effect sizes were found for upper body strength (Hedges' g = 1.70; p < 0.001) and lower body strength (Hedges' g = 1.40; p < 0.001). Following use of the Trim and Fill method (due to presence of publication bias), a large effect still remained for upper body strength (Hedges' g = 1.07), although a medium effect was found for lower body strength (Hedges' g = 0.52). A medium effect was found for muscular hypertrophy (g = 0.52, p = 0.002). Sub-analyses revealed that the moderating variables "training frequency" and "training volume" significantly influenced lower body muscular strength (p < 0.001). "Training frequency" and "sets per exercise" moderated the RT effects on upper body strength (p < 0.01). No moderating variables were found to significantly influence muscular hypertrophy. A trend for a moderating effect on upper body strength was found for "age of participants" (p = 0.08), whereby younger participants experienced a greater effect. A moderating effect was also observed where supervised training had a larger influence on the adaptation of lower body strength (p = 0.05) compared with unsupervised training. Methodological quality for the studies included in the review was found to be moderate. CONCLUSIONS: RT elicits large improvements in muscular strength and hypertrophy in healthy adult females. Training volume and frequency appear to be important variables that influence muscular strength.

Changes in Fatigue Are the Same for Trained Men and Women after Resistance Exercise.

PURPOSE: To measure changes in fatigue and knee-extensor torque in the 48 h after trained men and women completed a full-body resistance exercise session. METHODS: Eight trained women (mean ± SD: age, 25.6 ± 5.9 yr; height, 1.68 ± 0.06 m; mass, 71.0 ± 8.6 kg) and eight trained men (age, 25.5 ± 6.2 yr; height, 1.79 ± 0.05 m; mass, 86.4 ± 9.8 kg) performed a full-body resistance exercise session based on real-world athletic practice. Measurements were performed before and after the exercise session, as well as 1, 24, and 48 h after the session. Fatigue and pain were measured with standardized self-report measures. Maximal isometric contractions with the knee extensors and superimposed femoral nerve stimulation were performed to examine maximal torque, rate of torque development, voluntary activation, and muscle contractility. Two sets of 10 isokinetic contractions (60°·s) with the knee extensors were performed during the protocol with use of near-infrared spectroscopy to assess muscle oxygenation. EMG were recorded from two quadriceps muscles during all isometric and isokinetic contractions. RESULTS: Fatigue was increased from baseline for both sexes until 48 h after training (P < 0.001). Maximal torque and evoked twitch amplitudes were similarly reduced after exercise for men and women (P < 0.001). Voluntary activation and EMG amplitudes were unchanged after the training session. Muscle oxygenation was 13.3% ± 17.4% (P = 0.005) greater for women during the isokinetic repetitions, and the values were unchanged after the training session. CONCLUSIONS: This is the first study to show similar changes in the fatigue reported by trained men and women in the 48 h after a training session involving full-body resistance exercises. Sex differences in muscle oxygenation during exercise do not influence the reductions in muscle force, activation, or contractility after the training session.

Effect of Training Phase on Physical and Physiological Parameters of Male Powerlifters.

Longitudinal research on training and dietary practices of natural powerlifters is limited. This study investigated the effect of phases of training on physical and physiological parameters in male natural powerlifters. Nine participants completed testing at two time points: (i) preparatory phase (~3 months prior to a major competition) and (ii) competition phase (1-2 weeks from a major competition). No significant changes between training phases were found for muscle strength and power. A trend for significance was found for decreased muscle endurance of the lower body (-24.4%, p = 0.08). A significant increase in leg lean mass was found at the competition phase (2.3%, p = 0.04), although no changes for other body composition measures were observed. No change was observed for any health marker except a trend for increased urinary creatinine clearance at the competition phase (12.5%, p = 0.08). A significant reduction in training volume for the lower body (-75.0%, p = 0.04) and a trend for a decrease in total energy intake (-17.0%, p = 0.06) was observed during the competition phase. Despite modifications in training and dietary practices, it appears that muscle performance, body composition, and health status remain relatively stable between training phases in male natural powerlifters.