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This study investigated the effects of creatine and sodium bicarbonate coingestion on mechanical power during repeated sprints. Nine well-trained men (age = 21.6 ± 0.9 yr, stature = 1.82 ± 0.05 m, body mass = 80.1 ± 12.8 kg) participated in a double-blind, placebo-controlled, counterbalanced, crossover study using six 10-s repeated Wingate tests. Participants ingested either a placebo (0.5 g·kg−1 of maltodextrin), 20 g·d−1 of creatine monohydrate + placebo, 0.3 g·kg−1 of sodium bicarbonate + placebo, or coingestion + placebo for 7 days, with a 7-day washout between conditions. Participants were randomized into two groups with a differential counterbalanced order. Creatine conditions were ordered first and last. Indices of mechanical power output (W), total work (J) and fatigue index (W·s−1) were measured during each test and analyzed using the magnitude of differences between groups in relation to the smallest worthwhile change in performance. Compared with placebo, both creatine (effect size (ES) = 0.37-0.83) and sodium bicarbonate (ES = 0.22-0.46) reported meaningful improvements on indices of mechanical power output. Coingestion provided small meaningful improvements on indices of mechanical power output (W) compared with sodium bicarbonate (ES = 0.28-0.41), but not when compared with creatine (ES = -0.21-0.14). Coingestion provided a small meaningful improvement in total work (J; ES = 0.24) compared with creatine. Fatigue index (W·s−1) was impaired in all conditions compared with placebo. In conclusion, there was no meaningful additive effect of creatine and sodium bicarbonate coingestion on mechanical power during repeated sprints.

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Purpose To investigate changes in 24‐h energy expenditure (EE), substrate oxidation, and body composition following resistance exercise (RE) and a high protein diet via whey protein supplementation (alone and combined) in healthy older men. Methods In a pooled groups analysis, 33 healthy older men [(mean ± SE) age: 67 ± 1 years; BMI: 25.4 ± 0.4 kg/m2] were randomized to either RE (2×/week; n = 17) or non‐exercise (n = 16) and either a high protein diet via whey protein supplementation (PRO, 2 × 25 g whey protein isolate/d; n = 17) or control (CON, 2 × 23.75 g maltodextrin/d; n = 16). An exploratory sub‐analysis was also conducted between RE+CON (n = 8) and RE+PRO (n = 9). At baseline and 12 weeks, participants resided in respiration chambers for measurement of 24‐h EE and substrate oxidation and wore an accelerometer for 7 days for estimation of free‐living EE. Results Resistance exercise resulted in greater increases in fat‐free mass (1.0 ± 0.3 kg), resting metabolic rate [(RMR) 36 ± 14 kcal/d], sedentary EE (60 ± 33 kcal/d), and sleeping metabolic rate [(SMR) 45 ± 7 kcal/d] compared to non‐exercise (p < 0.05); however, RE decreased activity energy expenditure in free‐living (−90 ± 25 kcal/d; p = 0.049) and non‐exercise activity inside the respiration chamber (−1.9 ± 1.1%; p = 0.049). PRO decreased fat mass [(FM) −0.5 ± 0.3 kg], increased overnight protein oxidation (30 ± 6 g/d), and decreased 24‐h protein balance (−20 ± 4 g/d) greater than CON (p < 0.05). RE+PRO decreased FM (−1.0 ± 0.5 kg) greater than RE+CON (p = 0.04). Conclusion Resistance exercise significantly increased RMR, SMR, and sedentary EE in healthy older men, but not total EE. PRO alone and combined with RE decreased FM and aided body weight maintenance. This study was registered at clinicaltrials.gov as NCT03299972.

This study investigated age-related changes in trunk muscle function in healthy men and the moderating effect of physical activity. Twelve older (67.3 ± 6.0 years) and 12 younger (24.7 ± 3.1 years) men performed isokinetic trunk flexion and extension tests across a range of angular velocities (15°/s–180°/s) and contractile modes (concentric and eccentric). For concentric trunk extension, mixed-effects analysis of covariance revealed a significant interaction between Angular velocity × Age group (p = .026) controlling for physical activity. Follow-up univariate analysis of covariance revealed that the younger group produced significantly greater peak torque for all concentric extension conditions. Eccentric trunk strength was somewhat preserved in the older group. Age-related changes in trunk strength were independent of physical activity. The normal loss of trunk muscle strength in older age is muscle- and contractile-mode specific. These findings provide guidance for effective intervention strategies to offset adverse health outcomes related to trunk strength loss in older adults.

This study investigated age-related differences in trunk kinematics during walking in healthy men. Secondary aims were to investigate the covarying effects of physical activity (PA) and lumbar paravertebral muscle (LPM) morphology on trunk kinematics, and the effect of age on interplanar coupling between the trunk and pelvis. Three-dimensional (3D) trunk and pelvis motion data were obtained for 12 older (67.3 ± 6.0 years) and 12 younger (24.7 ± 3.1 years) healthy men during walking at a self-selected speed along a 10 m walkway. Phase-specific differences were observed in the coronal and transverse planes, with midstance and swing phases highlighted as instances when trunk and pelvic kinematics differed significantly (p < 0.05) between the younger group and older group. Controlling for age, fewer significant positive correlations were revealed between trunk and pelvic ranges and planes of motion. LPM morphology and PA were not significant covariates of age-related differences in trunk kinematics. Age-related differences in trunk kinematics were most apparent in the coronal and transverse planes. The results further indicate ageing causes an uncoupling of interplanar upper body movements during gait. These findings provide important information for rehabilitation programmes in older adults designed to improve trunk motion, as well as enable identification of higher-risk movement patterns related to falling.