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This investigation aimed to examine the acute effects of continuous and intermittent blood flow restriction (CBFR and IBFR, respectively) during sprint interval training (SIT) on muscle oxygenation, sprint performance, and ratings of perceived exertion (RPE). Fifteen men (22.6 ± 2.4 years; 176 ± 6.3 cm; 80.0 ± 12.6 kg) completed in random order a SIT session with CBFR, IBFR (applied during rest), and no blood flow restriction (NoBFR). Each SIT session consisted of two 30-second all-out sprint tests separated by 2 minutes. Peak power (PP), total work (TW), sprint decrement score (Sdec), RPE, and muscle oxygenation were measured during each sprint. A p value ≤ 0.05 was considered statistically significant. PP decreased to a greater extent from sprint 1 to sprint 2 during CBFR (25.5611.9%) and IBFR (23.4 ± 9.3%) compared with NoBFR (13.4 ±v 8.6%). TW was reduced similarly (17,835.6 ± 966.2 to 12,687.2 ± 675.2 J) from sprint 1 to sprint 2 for all 3 conditions, but TW was lower (collapsed across time) for CBFR (14,320.7 ± 769.1 J) than IBFR (15,548.0 ± 840.5 J) and NoBFR (15,915.4 ± 771.5 J). There were no differences in Sdec (84.3 ± 1.7%, 86.1 ± 1.5%, and 87.2 ± 1.1% for CBFR, IBFR, and NoBFR, respectively) or RPE, which increased from sprint 1 (8.5 ± 0.3) to sprint 2 (9.7 ± 0.1). Collective muscle oxygenation responses increased across time and were similar among conditions, whereas increases in deoxy[heme] and total[heme] were greatest for CBFR. Applying BFR during SIT induced greater decrements in PP, and CBFR resulted in greater decrements in work across repeated sprints. The larger increases in deoxy[heme] and total[heme] for CBFR suggested it may induce greater metabolite accumulation than IBFR and NoBFR when combined with SIT. [ABSTRACT FROM AUTHOR]

Abstract Purpose To determine the effects of 16 wk. of beta-hydroxy-beta-methylbutyrate (HMB) administration on age-related changes in functionality and diffusion tensor imaging (DTI) determined myofiber dimensions. Methods Twelve young (44 wk.), 6 middle-aged (60 wk.), 10 old (86 wk.), and 5 very old (102 wk.) male Fisher-344 rat's body composition and grip strength were assessed at baseline. Following, 6 young, 6 middle-aged, 5 old and 5 very old rats were sacrificed for baseline myofiber dimensions and gene transcript factor expression in the soleus (SOL) and gastrocnemius (GAS). The remaining 6 young and 5 old rats were given HMB for 16 wk. and then sacrificed. Results Fat mass increased in the middle-aged control condition (+49%) but not the middle-aged HMB condition. In addition, fat mass declined (-56%) in the old HMB condition but not the old control condition. Normalized strength declined and maintained respectively in the control and HMB conditions from 44 to 60 wk. and increased (+23%) (p < 0.05) from 86 to 102 wk. in only the HMB condition. Declines occurred in myofiber size in all muscles from 44 to 102 wk. in the control condition(-10 to -15%), but not HMB condition. Atrogin-1 mRNA expression in the SOL and GAS muscles was greater in the 102-wk control condition than all other conditions: SOL (+45%) and GAS (+100%). This elevation was blunted by HMB in the 102 wk. old SOL. There was a condition effect in the SOL for myogenin, which significantly increased (+40%) only in the 102-wk. HMB group relative to the 44-wk. group. Conclusions HMB may blunt age-related losses of strength and myofiber dimensions, possibly through attenuating the rise in protein breakdown.

Abstract Background The purpose of the present study was to examine the acute effects of a thermogenic nutritional supplement containing caffeine, capsaicin, bioperine, and niacin on muscular strength and endurance performance. Methods Twenty recreationally-active men (mean ± SD age = 21.5 ± 1.4 years; stature = 178.2 ± 6.3 cm; mass = 76.5 ± 9.9 kg; VO2 PEAK = 3.05 ± 0.59 L/min-1) volunteered to participate in this randomized, double-blinded, placebo-controlled, cross-over study. All testing took place over a three-week period, with each of the 3 laboratory visits separated by 7 days (± 2 hours). During the initial visit, a graded exercise test was performed on a Lode Corival cycle ergometer (Lode, Groningen, Netherlands) until exhaustion (increase of 25 W every 2 min) to determine the maximum power output (W) at the VO2 PEAK (Parvo Medics TrueOne® 2400 Metabolic Measurement System, Sandy, Utah). In addition, one-repetition maximum (1-RM) strength was assessed using the bench press (BP) and leg press (LP) exercises. During visits 2 and 3, the subjects were asked to consume a capsule containing either the active supplement (200 mg caffeine, 33.34 mg capsaicin, 5 mg bioperine, and 20 mg niacin) or the placebo (175 mg of calcium carbonate, 160 mg of microcrystalline cellulose, 5 mg of stearic acid, and 5 mg of magnesium stearate in an identical capsule) 30 min prior to the testing. Testing included a time-to-exhaustion (TTE) ride on a cycle ergometer at 80% of the previously-determined power output at VO2 PEAK followed by 1-RM LP and BP tests. Results There were no differences (p > 0.05) between the active and placebo trials for BP, LP, or TTE. However, for the BP and LP scores, the baseline values (visit 1) were less than the values recorded during visits 2 and 3 (p ≤ 0.05). Conclusion Our findings indicated that the active supplement containing caffeine, capsaicin, bioperine, and niacin did not alter muscular strength or cycling endurance when compared to a placebo trial. The lack of increases in BP and LP strength and cycle ergometry endurance elicited by this supplement may have been related to the relatively small dose of caffeine, the high intensity of exercise, the untrained status of the participants, and/or the potential for caffeine and capsaicin to increase carbohydrate oxidation.

The article focuses on a study which compared changes in muscle architecture and performance in starters and nonstarters during a National Collegiate Athletic Association Division I women's soccer season in the U.S. The researchers designed a strength and conditioning program. Playing time during matches was not found to have much effect on the results.

Although creatine has been mostly studied as an ergogenic aid for exercise, training, and sport, several health and potential therapeutic benefits have been reported. This is because creatine plays a critical role in cellular metabolism, particularly during metabolically stressed states, and limitations in the ability to transport and/or store creatine can impair metabolism. Moreover, increasing availability of creatine in tissue may enhance cellular metabolism and thereby lessen the severity of injury and/or disease conditions, particularly when oxygen availability is compromised. This systematic review assesses the peer-reviewed scientific and medical evidence related to creatine's role in promoting general health as we age and how creatine supplementation has been used as a nutritional strategy to help individuals recover from injury and/or manage chronic disease. Additionally, it provides reasonable conclusions about the role of creatine on health and disease based on current scientific evidence. Based on this analysis, it can be concluded that creatine supplementation has several health and therapeutic benefits throughout the lifespan. [ABSTRACT FROM AUTHOR]

Many previous studies have reported a temporary decrease in muscle strength following an acute bout of stretching, which has been termed the “stretching-induced force deficit.” It has also been suggested that the stretching-induced force deficit may be joint angle-specific and influenced by initial level of flexibility. To examine the effects of initial flexibility on the stretching-induced force deficit in the plantar flexor muscles at multiple joint angles and ankle joint range of motion (ROM). Fourteen men with limited dorsiflexion ROM (mean age ± SD = 21 ± 2 yrs; stature = 173 ± 9 cm; mass = 75 ± 12 kg; dorsiflexion ROM = 11 ± 6°) and 14 men with a normal ROM (22 ± 2 yrs; 177 ± 8 cm; 75 ± 14 kg; 28 ± 6°) (Roaas et al. 1982, Acta Othropedic 53(2): 205 - 208) performed stretch tolerance assessments and isometric maximal voluntary contractions (MVCs) at -19°, -9°, 1°, and 12° of dorsiflexion (0° = neutral ankle joint angle) designed to examine the ROM and strength, respectively. Testing was performed on a custom-built load cell apparatus attached to a calibrated isokinetic dynamometer before and after a bout of passive stretching. To assess stretch tolerance, the dynamometer lever arm passively dorsiflexed the foot at 5°·s-1 from -20° of dorsiflexion to the maximum tolerable ROM (as acknowledged by the subjects). For the MVC assessments, subjects were instructed to provide maximal force of the plantar flexors for 4 s at each randomly-ordered joint angle. The position signal (°) from the dynamometer and force signal (N) from the load cell were sampled at 1 KHz during the flexibility and strength assessments, respectively. The passive stretching protocol consisted of nine 135-s constant-torque passive stretches, which was held by the dynamometer at each subject's maximum tolerable passive stretching force (the point of discomfort). Five to 10 s was allowed between each stretching repetition. A three way mixed factorial ANOVA [time × angle × group; 2 × 4 × 2] was used to analyze the MVC data, while a two way mixed factorial ANOVA [time × group; 2 × 2] was used to analyze the ROM data. There was a 9% decrease in plantar flexor MVC strength from pre- to post-stretching across all joint angles for both groups (p < 0.001). Conversely, there was a 4% increase in dorsiflexion ROM from pre- to post-stretching for both groups (p < 0.001), however, the normal ROM group had higher dorsiflexion ROM values than the limited ROM group (p < 0.001) at all time points. The magnitude of change for MVC strength and dorsiflexion ROM from pre- to post-stretching was not affected (p > 0.05) by the joint angle or limitations of ROM. These findings suggested that the initial level of flexibility does not influence the force deficit or increases in dorsiflexion ROM following an acute bout of passive stretching in the plantar flexor muscles. These results also indicated that the stretching-induced force deficit occurs at all the ankle joint angles tested. These findings may be useful for strength and conditioning professionals or other allied health practitioners who may incorporate stretching prior to testing or performance. Regardless of initial flexibility, 20 min of passive stretching appears to increase dorsiflexion ROM, but decrease the maximal strength capabilities of the plantar flexors at all of the joint angles tested in the present study. [ABSTRACT FROM AUTHOR]