Recent studies suggest that a substantial proportion of athletes with spinal cord injury have insufficient 25(OH) vitamin D (25(OH)D) status, which may be associated with decreased muscle strength. This study consisted of two parts: (a) to examine the effects of a 12- to 16-week vitamin D3 supplementation protocol on 25(OH)D concentration and (b) to determine whether subsequent 25(OH)D status impacts muscle performance in elite athletes with spinal cord injury. Thirty-four members (age: 33 ± 15 years, weight: 69.6 ± 28.2 kg, and height: 170.2 ± 25.4 cm) of the U.S. and Canadian Paralympic program participated in the study. 25(OH)D concentrations and performance measures (handgrip strength and 20-m wheelchair sprint) were assessed pre- and postsupplementation. Participants were assigned a vitamin D3 supplementation protocol based on initial 25(OH)D concentrations. Participants with deficient 25(OH)D status (<50 nmol/L) received 50,000 IU/week for 8 weeks, and participants with insufficient status (50–75 nmol/L) received 35,000 IU/week for 4 weeks, after which both received a maintenance dose of 15,000 IU/week. Participants with sufficient status (>75 nmol/L) received the maintenance dose of 15,000 IU/week. 25(OH)D concentrations increased significantly (p < .001; 66.3 ± 24.3 nmol/L and 111.3 ± 30.8 nmol/L pre- and postsupplementation, respectively). About 26% of athletes had sufficient 25(OH)D concentrations presupplementation, and 91% had sufficient concentrations postsupplementation. About 62% of participants improved handgrip strength postsupplementation with no change in 20-m wheelchair sprint performance. The supplementation protocol was effective for achieving sufficient vitamin D concentrations in elite athletes with spinal cord injury.
Kelly Pritchett, Robert C. Pritchett, Lauren Stark, Elizabeth Broad and Melissa LaCroix
J. Matt Green, P. Jason Wickwire, John R. McLester, Shawn Gendle, Geoffrey Hudson, Robert C. Pritchett and C. Matt Laurent
Ergogenic effects of caffeine on aerobic or endurance exercise are well documented. Conversely, the ergogenic value of caffeine on high-intensity, primarily anaerobic performance is not well understood even though the proposed mechanisms of action for caffeine permit a strong theoretical basis for application to this type of exercise.
This study examined effects of caffeine (Ca) on number repetitions (reps), ratings of perceived exertion (RPE), and peak heart rate (PHR) during resistance-training exercise with reps performed to volitional failure.
Subjects (N = 17) were tested for 10-rep maximum in bench press (BP) and leg press (LP). In sessions 2 and 3, Ca (~6 mg/kg) or placebo (Pl) was ingested 1 hr beforehand in a double-blind manner and counterbalanced order. Subjects performed 3 sets to failure (BP and LP) with reps, PHR, and RPE recorded each set. Repeated-measures ANOVAs, 2 (trial) × 3 (set), were used to analyze dependent measures with the Tukey honestly significant difference used when necessary as the post hoc test.
In BP, no significant differences (Ca vs Pl) were observed (reps, RPE, PHR). During set 3 of LP training, Ca was associated with significantly higher reps (12.5 ± 4.2 vs 9.9 ± 2.6) and PHR (158.5 ± 11.9 vs 151.8 ± 13.2). No signifcant RPE differences were found during LP.
The findings of similar RPE concurrent with higher reps suggest that caffeine can blunt pain responses, possibly delaying fatigue in high-intensity resistance training. Ergogenic effects might be limited to the later sets in a resistance-training session. Further research is warranted regarding ergogenic effects of caffeine during resistance training and potential mechanisms of action.