Search Results (455)

Population aging has markedly increased the burden of cancer in older adults, in whom frailty, sarcopenia, and reduced physiological reserve limit tolerance to treatment and worsen clinical outcomes. Aging is accompanied by progressive functional decline and by biological processes such as cellular senescence, characterized by irreversible cell cycle arrest, chronic low-grade inflammation, and impaired immune surveillance. The accumulation of senescent cells and the persistence of a senescence-associated secretory phenotype contribute to tissue dysfunction and generate a microenvironment that favors tumor initiation and progression. Physical exercise has been associated with attenuation of inflammation, improvements in metabolic and immune function, and with lower levels of senescence-related biomarkers. Although aerobic exercise has been extensively studied in this setting, resistance training holds relevance for older adults due to its capacity to counteract sarcopenia, preserve muscle strength and power, and sustain functional independence. Structured and periodized approaches to resistance exercise may further enhance these benefits by delivering targeted stimuli aligned with age-related physiological deficits. Block strength training (BST), a periodized model that concentrates training adaptations into sequential phases of maximal strength, power, and muscular endurance, has demonstrated consistent improvements in functional performance and reductions in frailty risk in community-dwelling older adults. BST improves physical function. It may also influence biological processes related to aging and cancer; however, mechanistic evidence specific to BST remains to be established. We hypothesized that the exercise in block as a targeted, a structured and physiologically grounded resistance training intervention highlights the potential of BST to promote functional aging and healthy. In the case of cancer biology, and the environment near to tumour, the relationship between aging mechanisms in older adults and controlled exercise effects are currently in advance, but mechanistic trials are still lacking. Finally, we propose a novel training method, structured and personalized, that could impact different clinical outcomes in older patients with cancer. Full article

Despite the widespread use of periodized resistance training by athletes, the acute physiological and performance responses when athletes transition between mesocycles with differing workload volumes remain poorly understood. This study examined the acute effect of increasing resistance training workload volume on muscle damage markers and field-specific performance in heavy resistance-trained youth athletes. Eighteen male, rugby league players (age 17.4 ± 0.8 years; body mass 80.2 ± 13.7 kg; height 1.8 ± 0.1 m) completed a four-week mesocycle to develop maximal strength (70–100% of one repetition maximum [1RM]). Muscle damage (i.e., delayed onset muscle soreness [DOMS] and creatine kinase [CK]) and performance measures (i.e., drop jump, plyometric push-up, 40 m sprint and repeated agility) were assessed prior to and at 24 h (T24) and 48 h (T48) following the last session of the strength mesocycle (Week 5). A hypertrophy session (35–70% of 1RM) was then included in Week 6 with data collected prior to and at T24 and T48. Compared with the strength (Week 5) modality, the hypertrophy (Week 6) modality resulted in greater DOMS (41.6 ± 22.7%; effect size [ES] = 0.97–1.12) and modestly higher CK (26.7 ± 47.8%; ES = 0.6). Larger declines in field-specific performance measures were also shown during the HYP modality than STR modality for 20 m sprint performance (−2.1 ± 4.3%; ES = 0.7) and agility performance (−1.1 ± 4.2%; ES = 0.6). There were more modest reductions in drop jump performance (−4.1 ± 7.2%; ES = 0.7) during the HYP modality than in the STR modality, although caution should be given as two separate force plate systems were combined due to technical difficulties. Increasing workload volume was associated with greater muscle damage and modest differences in selected field-specific performance measures following several weeks of maximal strength training. These findings provide preliminary insight into the acute responses to increases in resistance training workload volume. Coaches should monitor athletes’ acute responses during fluctuations in workload volume and consider strategies to help maintain training quality in youth athletes. Full article

Strength training (ST) is commonly implemented to enhance soccer-related fitness qualities such as sprinting, jumping, and changes-of-direction while also contributing to injury risk reduction. It is traditionally emphasized in the pre-season period. In-season ST may confer these benefits, but it can also induce muscle damage and inflammation. To examine the effects of a 12-week in-season ST program on maximal dynamic strength, muscle damage biomarkers, and inflammatory biomarkers, 24 elite young female soccer players (Tier 4 according to the McKay et al. classification) aged 14.9 ± 0.8 years and a maturity offset of +2.6 ± 1.1 years were randomly allocated to an ST group (STG, n = 12) or an active control group (CG, n = 12). Both groups followed the same soccer training program. However, in the STG, two weekly soccer sessions were replaced with ST. Overall training volume was comparable between groups. Maximal dynamic strength (1-RM tests for bench press, lat pull-down, and leg press), blood biomarkers of muscle damage (creatine phosphokinase [CPK], lactate dehydrogenase [LDH]), and inflammation (interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]) were assessed before (T1) and after (T2) the interventions. Analyses showed significant increases for STG for the 1-RM bench press, the 1-RM lat pull-down, and the 1-RM leg press (p < 0.001). No significant interactions were detected for any blood marker of muscle damage (LDH and CPK) or inflammation (IL-6 and TNF-α) (all p > 0.05). Results support a 12-week in-season ST program improved maximal dynamic strength in elite young female soccer players without altering resting levels of muscle damage or inflammatory markers measured 48 h after training compared to regular soccer training. These findings suggest that ST can be safely implemented during the competitive season in young female soccer players without overreaching or overtraining. Full article

Background and Objectives: Obesity affects over 1.9 billion adults globally, with a disproportionately higher prevalence in Saudi Arabia among women. While excessive adiposity is known to impair respiratory mechanics and lung function, its relationship with respiratory muscle strength and exercise energy expenditure remains inadequately elucidated. This study examined differences in respiratory muscle strength, metabolic equivalents (METs) of physical activity, and energy expenditure during exercise between adults with normal and high body fat percentage (BF%) and explored the statistical role of body fat as a potential mediator in the cross-sectional association between respiratory muscle strength and energy expenditure. Methods: In this cross-sectional study, 126 Saudi women aged 18–45 years (mean age: 21.7 ± 4.2 years) were stratified into normal (n = 63) and high (n = 63) BF% groups. Body composition was assessed via bioelectrical impedance analysis, and respiratory muscle strength (MIP and MEP) was measured using a MicroRPM device. Peak oxygen consumption (VO_2peak) and energy expenditure were obtained through the Bruce Submaximal Treadmill Protocol, and physical activity was self-reported via the IPAQ. Hierarchical regression and structural equation modeling were used to examine variable associations and explore statistical mediation patterns. Results: Participants with high body fat demonstrated significantly low MIP (−26%) and MEP (−31%), low VO_2peak (−13%), and approximately 26% high energy expenditure during exercise compared to the normal-BF group (all p < 0.001), despite comparable self-reported physical activity levels. Body fat percentage was the most strongly associated with energy expenditure (β = 0.078, R² = 0.329), with maximal inspiratory pressure contributing an additional 7.3% of explained variance in hierarchical regression (total R² = 0.414). Mediation analyses revealed that body fat percentage was statistically consistent with a partial mediation model in the relationship between MIP and energy expenditure (indirect association = −0.016, p = 0.033), accounting for 27% of the total association, and between MEP and energy expenditure (indirect association = −0.013, p = 0.035), accounting for 38% of the total association. Conclusions: High BF% is independently associated with low respiratory muscle strength and high exercise metabolic cost. Body fat is statistically associated with (and consistent with a mediating role in) an inverse relationship between respiratory muscle strength and energy expenditure. Alternative directional relationships and shared underlying factors may explain these observations. Full article

Background and Objectives: The hypertrophic adaptation of the diaphragm to inspiratory muscle training (IMT) remains insufficiently characterized, particularly in healthy and athletic populations. To address this gap, we conducted a meta-analysis and meta-regression to evaluate the effects of IMT on diaphragm thickness and identify potential moderating factors. Materials and Methods: A systematic search was conducted across PubMed, MEDLINE, Embase, CINAHL, and SPORTDiscus as well as Google Scholar (gray literature) through November 2025. Eight studies involving 203 healthy participants met the inclusion criteria. A random-effects model was used to calculate pooled effect sizes and meta-regression estimates. Results: IMT produced a statistically significant moderate increase in diaphragm muscle thickness, with a standardized mean difference (SMD) of Hedges’ g = 0.52 (95% CI: 0.19 to 0.85; p < 0.05). Subgroup analyses indicated that IMT with 50% maximal inspiratory pressure (MIP) produces a statistically significant effect (p = 0.0069), whereas fitness status and age did not significantly influence outcomes (p = 0.589 and p = 0.126, respectively). Meta-regression analyses revealed that only baseline MIP value (β = 0.030; 95% CI: 0.009 to 0.050; p = 0.004) was associated with diaphragm hypertrophy. Conclusions: IMT with 50% of MIP elicits meaningful diaphragmatic hypertrophy in healthy individuals. This response appears independent of fitness status or age, but is significantly influenced by baseline inspiratory muscle strength (MIP). These findings support the utility of IMT in enhancing respiratory muscle morphology in health and performance contexts. Full article

(1) Achilles tendon rupture is one of the most severe lower-limb injuries, frequently occurring during movements involving maximal dorsiflexion with the knee at near-full extension. Preventive strategies are crucial, particularly for athletes engaged in high-risk sports such as basketball. (2) In this work, we examined the effect of a novel Achilles brace on Achilles tendon loading during concentric and eccentric mechanisms associated with tendon rupture. (3) Twenty-eight young basketball players performed tests under two conditions: with the adaptive brace and without it (control). Participants were divided into two groups (n = 14 in both). The first group assessed concentric Achilles loading by performing three plantar-flexor strength tests in three different joint configurations: maximal dorsiflexion with the knee flexed (FKF); injury mechanism position—full plantar flexion with the knee extended (FKE); and neutral ankle position with the knee extended (NKE). The number of maximal heel-raise repetitions performed before onset of fatigue was recorded. The second group assessed eccentric tendon loading by performing single-leg forced maximal-velocity dorsiflexion with the knee extended. In all tests, the time between maximal plantar flexion and maximal dorsiflexion, as well as the ankle range of motion, was analyzed using 2D video. Paired t-tests were used to compare braced and control conditions. In all tests, the ankle range of motion (ROM) did not differ significantly between brace and control conditions. Wearing the brace significantly improved plantar-flexor muscle strength only in the FKE test (31 ± 1.3 repetitions with brace vs. 21 ± 1.3 in control, p < 0.05). No significant differences were found for the FKF (27 ± 1.3 vs. 25 ± 1.3) or NKE (25 ± 1.3 vs. 24 ± 1.3) positions. During drop eccentric loading, wearing the brace resulted in a significantly slower transition time from plantar flexion to dorsiflexion (460 ± 60 ms with brace vs. 320 ± 30 ms in control, p < 0.001). (4) In brief, the novel Achilles brace was found to significantly reduces Achilles tendon load during both concentric and eccentric activities, but only in high-risk joint positions. These findings suggest that the brace provides mechanical protection, and may reduce the risk of Achilles tendon rupture, in athletes exposed to high tendon stress. Full article

This study investigated how varying body positions (seated, prone, supine) and knee joint angles (90°, 120°, 150°) influence the bilateral deficit (BD) in isometric hamstring strength. Thirty physically active participants (15 males, 15 females) performed unilateral and bilateral maximal voluntary isometric contractions (MVICs) across the tested position × angle conditions. Peak force (Fmax) and rate of force development (RFD) measures (RFDmax, RFD50 ms, and RFD200 ms) were recorded. Results indicated that the seated position elicited a greater bilateral deficit (i.e., lower BD ratios) than the prone and supine positions, with differences that were more pronounced at more extended knee angles. These findings underscore the importance of considering position- and angle-specific influences when assessing BD in hamstring strength. Clinicians and researchers should standardize testing protocols to ensure accurate evaluation and data interpretation. From an applied standpoint, the results support the development of resistance-training strategies aimed at enhancing hamstring function at long muscle lengths—an approach relevant to both performance optimization and injury prevention. Full article

Background and Objectives: Cross-country skiing requires high levels of upper-body strength and efficient respiratory function to sustain performance during sport-specific movements. This study aimed to examine the effects of an eight-week ski ergometer-based training program on upper-extremity isokinetic muscle strength and pulmonary function in competitive cross-country skiers. Materials and Methods: A total of 20 cross-country skiers voluntarily participated in the study (experimental group: n = 10, control group: n = 10). The research was conducted using a quasi-experimental controlled design. During the eight-week training period, the experimental group performed ski ergometer training three times per week at an intensity of 80–90% of maximal heart rate, with a target distance of 2.5 km per session, in addition to their regular training program. Measurements were obtained before and after the intervention. Results: Following the ski ergometer training period, significant increases were observed in FVC (F = 18.565, p < 0.001, ηp² = 0.508) and FEV₁ (F = 8.789, p = 0.008, ηp² = 0.328), which were associated with enhanced respiratory muscle endurance and ventilatory capacity. Regarding the isokinetic strength parameters, the DPPE60 variable showed significant main effects of time (F = 33.770, p < 0.001, ηp² = 0.652) and time × group interaction (F = 18.590, p < 0.001, ηp² = 0.508), indicating higher upper-extremity strength values across the measurement period. Additionally, strong positive correlations were found between dominant and nondominant limbs (r = 0.79–0.92; p < 0.05), indicating balanced bilateral strength development and high neuromuscular coordination. Conclusions: Ski ergometer-based training was associated with improvements in upper-extremity peak power (DPPE60) and ventilatory capacity (FVC) beyond general training-related adaptations. These findings suggest that SkiErg training may be a useful complementary method for enhancing selected performance-related physiological parameters in cross-country skiers. Full article

Background: This study compares the effects of relativized barbell loads (% of one-repetition maximum or 1RM) versus standardized prescribed loads on High-Intensity Functional Training (HIFT) performance, strength adaptations, physiological response, and perceived effort. Methods: In total, 22 experienced HIFT athletes (12 males, 10 females) were randomly assigned to either a standardized load (SL) or relativized load (RL) group. Both groups completed an 8-week HIFT program with benchmark workouts. Performance was assessed using a local muscle endurance test, maximal strength through 1RM testing (back squat, clean, and clean and jerk), and neuromuscular performance via countermovement jump (CMJ). Cardiopulmonary response (VO²peak, VO²mean, heart rate, and blood lactate levels) and perceived effort (Borg CR-10) were also evaluated. Results: RL participants did not show a difference in the interaction between group and time in TT performance but differences were founded for strength gains in back squat (p = 0.005, 95% CI [3.1, 8.6]) and clean (p = 0.027, 95% CI [1.2, 5.7]) compared to the SL group. No significant differences were found in clean and jerk performance or CMJ height. Cardiopulmonary responses were similar between groups, indicating comparable physiological stress. RL participants reported significantly lower perceived exertion (p < 0.001, 95% CI [6.3, 9.8]), suggesting more efficient load management and recovery. Conclusions: Use of individualized loads based on 1RM enhanced HIFT performance and strength adaptations, without increasing physiological stress, enabling more efficient training with reduced fatigue. Full article

Sarcopenia is a complex condition marked by reductions in muscle strength, mass, and overall physical performance, which has significant consequences for functional autonomy and metabolic health in elderly women. This study aimed to examine the correlations between lower limb strength, functional capabilities, and metabolic indicators in community-dwelling older women categorized according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria. A total of thirty-eight women aged ≥ 60 years underwent assessments, including anthropometric, hemodynamic, and metabolic evaluations, along with functional tests such as handgrip strength, chair-rise test, gait speed, Timed Up-and-Go, and maximal isometric hip extension strength (MIHE). The criteria for probable sarcopenia were established using the handgrip thresholds set by the EWGSOP2. Women identified as having probable sarcopenia displayed markedly lower MIHE, diminished gait speed, inferior performance in chair-rise and Timed Up-and-Go tests, decreased muscle mass, and a lower resting metabolic rate than their non-sarcopenic counterparts. MIHE exhibited robust correlations with muscle mass, resting metabolic rate, and functional performance metrics. These results suggest that assessments of lower limb and trunk strength yield pertinent insights beyond handgrip strength alone. Function-oriented evaluations may improve sarcopenia screening and facilitate the identification of older women at risk of functional and metabolic deficiencies in community-based environments. Full article

Background: Low estrogen levels during menopause reduce nitric oxide (NO) production, contributing to decline in skeletal muscle quality and function. Although acute and short-term dietary nitrate supplementation has demonstrated promising effects, long-term benefits, particularly on muscle quality in postmenopausal women, are not well established. Objectives: The objective was to investigate the effects of long-term (12-week) nitrate-rich beetroot extract supplementation on morphological and functional muscle quality, rate of force development (RFD), maximal strength, and circulating nitrate/nitrite concentrations in postmenopausal women. Methods: In a randomized, double-blind, placebo-controlled design, 20 postmenopausal women (21 years ± 7 since menopause) consumed 20 g/day of a nitrate-rich beetroot extract (BET; 548 mg nitrate/day) or a nitrate-depleted beetroot extract (PLA; 43 mg nitrate/day) for 12 weeks. Outcome measures, including muscle quality (functional via muscle strength/thickness ratio; morphological via ultrasound echo intensity), RFD, maximal voluntary isometric contraction (MVIC), and serum nitrate/nitrite levels, were evaluated at baseline, 8 weeks, and 12 weeks. Results: BET significantly increased serum nitrate (0.005) and nitrite (0.022) levels compared to PLA at both week 8 and week 12. Morphological muscle quality also improved significantly in the BET group (interaction effect, p = 0.014). Early-phase rate of force development (RFD) increased between 30 and 100 ms, whereas late-phase RFD increased between 100 and 200 ms. RFD_peak also improved by week 8, and these gains were maintained through week 12 (interaction effect, p < 0.05). Although there was no significant difference between groups for functional muscle quality, MVIC increased at week 12 in the BET group, but no significant Time × Group interaction was observed. Conclusions: Twelve weeks of nitrate-rich beetroot extract supplementation improved morphological muscle quality and RFD, suggesting potential clinical relevance for preventing structural and neuromuscular function decline in postmenopausal women. This study was registered with ReBEC (RBR-87qh649) and approved on 8 October 2024. Full article

Introduction: Muscle function is influenced by hydroelectrolytic mechanisms that regulate cellular volume beyond isolated plasma electrolyte concentrations. However, the role of integrated hydration and electrolyte regulation profiles in muscle function among older adults remains insufficiently understood. Objective: To identify which physiological domains of hydroelectrolytic regulation are most strongly associated with muscle strength and functional performance in community-dwelling older adults. Methods: A cross-sectional study was conducted in 96 community-dwelling individuals aged ≥ 70 years. Markers of cellular hydration and membrane integrity were assessed using bioelectrical impedance analysis, together with first-morning fasting plasma and urinary sodium and chloride concentrations. Principal component analysis (PCA) was applied as a data-driven approach to identify latent domains of coordinated hydroelectrolytic regulation. Associations between component scores and handgrip strength and Timed Up and Go (TUG) were examined using two sequential multivariable regression models: Model 1 adjusted for sex and fat-free mass index (FFMI); Model 2 additionally adjusted for age, hypertension, and diuretic use. Results: Three principal components were retained, explaining 77.5% of total variance: PC1 (renal–cellular domain), PC2 (plasma electrolyte domain), and PC3 (cellular volume domain). For handgrip strength, Model 1 showed significant associations for PC3 (β = 0.152; p = 0.025) and PC1 (β = 0.180; p = 0.050). In Model 2, only PC3 remained independently associated (β = 0.146; p = 0.036). For TUG, Model 1 showed associations for PC1 (β = −0.262; p = 0.049) and PC3 (β = −0.238; p = 0.015). In Model 2, PC1 (β = −0.308; p = 0.019) and PC2 (β = −0.190; p = 0.046) remained independently associated, whereas PC3 was not. Conclusions: Maximal force production appears primarily associated with cellular volume regulation, whereas functional performance reflects broader multi-compartmental hydroelectrolytic integration involving renal and plasma domains. These findings suggest that multidimensional hydration profiling may complement isolated biochemical markers in the functional assessment of older adults, warranting validation in longitudinal studies. Full article

Background/Objective: Post-COVID survivors present significant respiratory deficiency that has been associated with ongoing shortness of breath and impaired lung function. Inspiratory muscle training (IMT) is increasingly used in survivors of COVID-19 rehabilitational programs as a means to facilitate recovery of the respiratory system. Yet, its home-based effectiveness across clinically relevant outcomes remains unclear. This systematic review aimed to present current evidence on home- or tele-delivered IMT in the post-COVID-19 population. Methods: PubMed, Scopus, Cochrane library and Science Direct were systematically searched for studies evaluating home-based (or telerehabilitation) IMT, alone or as part of a respiratory muscle training program, in adults with post-COVID-19 symptoms. The primary outcome was inspiratory muscle strength. Secondary outcomes included dyspnea, pulmonary function, exercise capacity and health-related quality of life. The methodological quality of the included studies was assessed via the PEDro scale. Owing to clinical and methodological heterogeneity, we performed only a qualitative synthesis. Results: Eight studies met the inclusion criteria. Two included both inspiratory and expiratory muscles training and three included physical training as well. The methodological quality was found to be good. IMT consistently increased inspiratory muscle strength across trials. Respiratory muscle training (RMT) programs that combined inspiratory and expiratory training also improved maximal expiratory pressure. IMT reduced dyspnea versus control/sham or baseline and several studies reported improvements in exercise capacity and physical function. Spirometry/DLCO changes were small or null in most cohorts. HRQoL gains were domain-specific in anxiety and depression. Adherence was generally good. No serious adverse events attributable to IMT were reported. Conclusions: Home-based IMT for adults with post-COVID-19 conditions is safe and seems to improve inspiratory muscle strength and dyspnea, with signs of benefit for exercise capacity, physical function, and selected HRQoL domains. Effects on ventilatory efficiency and conventional lung function appear limited. Future multicenter, sham-controlled RCTs should further explore the characteristics of IMT, employ core outcome sets, include longer follow-up, and predefine phenotype-based subgroups. Full article

Background: Tubular aggregate myopathy (TAM) is an autosomal dominant myopathy that results from gain-of-function mutations in the STIM1 and ORAI1 genes, which encode the two key proteins that coordinate store-operated Ca²⁺ entry in skeletal muscle and other cell types. Knock-in mice heterozygous for a glycine-to-serine point mutation in the ORAI1 pore (ORAI1^G100S/+ or GS mice) phenocopy several key aspects of TAM in humans with the analogous mutation including muscle weakness, exercise intolerance, elevated CK levels, hypocalcemia, and the presence of tubular aggregates. Methods: Since homozygous inheritance of the ORAI1-G100S mutation is embryonic lethal, we assessed the impact of homotypic ORAI1-G100S expression in skeletal muscle by crossing GS mice with constitutive, muscle-specific ORAI1 knock-in mice (cORAI1-KO). Results: Compound cORAI1-KO/GS mice exhibit only one active ORAI1 (GS) allele, and thus only express ORAI1-G100S monomers in skeletal muscle (‘homotypic’ GS mice). Homotypic GS mice exhibit an earlier onset and more severe muscle phenotype than age-matched heterotypic GS mice with both WT and GS alleles. Specifically, homotypic GS mice exhibit TAs at an earlier age, as well as significantly reduced in vivo muscle performance (grip strength, treadmill endurance, and rotarod endurance), maximal specific force production, and respiratory function, compared to those observed for both WT and heterotypic GS mice. Conclusions: These findings indicate that homotypic expression of the ORAI1-G100S mutation in skeletal muscle results in an earlier-onset and more severe muscle phenotype. Full article

Objectives: To determine whether caffeine supplementation and its expectancy influence muscle strength (ST) and muscle endurance (ME) using a balanced-placebo design. Methods: Using a randomized, double-blind, balanced-placebo design, resistance-trained men (18–30 years; n = 16) participated in two assessment/familiarization visits (demographics; one repetition maximum (1RM) followed by four counterbalanced sessions: C/C (informed caffeine/used caffeine), P/C (informed placebo/used caffeine), C/P (informed caffeine/used placebo), P/P (informed placebo/used placebo). Caffeine dose was 5 mg/kg. Peak torque (PT) and maximum work (MW) were measured in the knee extensors at 0, 60, 180, and 300°/s, which was followed by ME testing (three sets of maximal repetitions using 60%1RM). Capillary blood lactate was measured after ME testing. Results: Caffeine increased PT only during static and 60°/s contractions (4%; p ≤ 0.003; d = 0.3 for both speeds), while MW increased across all speeds (4%; p < 0.001; d = 0.2). Caffeine did not increase ME (3%; p = 0.184; d = 0.1), but it did increase blood lactate levels (1.2 mmol/L; p < 0.001; d = 0.7). Caffeine expectation did not improve ST or ME, but increased blood lactate levels (0.7 mmol/L; p = 0.003; d = 0.4). Across ST and ME, responses to caffeine were markedly heterogeneous, with 50–88% of individuals considered responders (∆ > 0), and improvements in responders ranged from 1–16%. Conclusions: Caffeine significantly increased ST, despite ME increasing in 50% of participants, this was not significant. No placebo effect was observed in ST or ME, but it significantly increased lactate. Further research is necessary to elucidate the mechanisms behind this variability in the ME response, especially the role of fiber-type predominance. Full article