RESEARCH

Aim:
We investigated the effect of ischemic preconditioning (IPC) on the repeated sprint ability (RSA) of elite Olympic-level male rugby 7s athletes.

Methods:
In a double blind, crossover study, 12 males (age 23 ± 4 years; stature 1.85 ± 0.07 cm; body mass 91.0 ± 7.0 kg; sum of 7-sites 52.2 ± 12.0 mm; YoYo IR1 19.3 ± 1.0) completed a RSA test (3 x (6 x 15 m + 15 m, 20 s recovery between reps and 120 s between series)) preceded 90 minutes by IPC treatment (4 x 5 min on/off at 220 mmHg bilateral leg occlusion) or Sham (4 x 5 min on/off at 20 mmHg bilateral leg occlusion).

Results:
No difference was found between the IPC and sham fastest or slowest sprint times, or when compared across all 18 sprints, with no intervention-sprint time interaction effect (p > 0.05). The percentage decrement across the 18 sprints was not significantly different between IPC and Sham interventions (p > 0.05). The accumulated four intervention pressure periods for ∆TSI% and ∆HHb were significantly greater in a negative and positive direction respectively for IPC compared with sham (p < 0.05).

Conclusion:
IPC did not negatively affect repeated sprint performance in elite male rugby 7s athletes. Peripheral oxygenation does not appear to be a limiting factor for RSA in elite male rugby 7s athletes.

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Aim:
We investigated the effect of ischemic preconditioning (IPC) on critical power (CP) during a 3-minute all-out test. Design: Randomized, crossover

Methods:
Twelve males (mean ± SD: age 30 ± 6 years; stature 1.82 ± 0.07 m; mass 82.1 ± 10.7 kg; V̇O2peak4.18 ± 0.86 L.min-1) completed two 3-minute all-out tests immediately preceded by either sham (4 x 5 minute on/off at 20 mmHg bilateral leg occlusion) or IPC treatment (4 x 5 minute on/off at 220 mmHg bilateral leg occlusion). CP was calculated as the mean power output during the final 30 s of the test, W’ as the work done above CP, total work done (TWD) was calculated throughout each 3-minute test and tissue saturation index (TSI) and deoxygenation (HHb) measured using near-inferred spectroscopy (NIRS).

Results:
During the IPC / sham stimulus there was a 15.3 ± 0.3% decrease in TSI in the IPC trial, relative to sham. IPC resulted in an increase in CP compared with sham (241 ± 65 W vs. 234 ± 67 W, respectively, p < 0.05). There were no differences between sham and IPC for W’ (18.4 ± 3.8 vs 17.9 ± 3.7 kJ, respectively) or TWD (61.1 ± 12.7 vs 60.8 ± 12.7 kJ, respectively).

Conclusion:
IPC enhanced CP during a 3-minute all-out cycling performance in healthy, physically active males, with no changes observed for W’ or TWD.

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Aim:
We investigated the effect of ischemic preconditioning (IPC) on the repeated sprint ability (RSA) of elite Olympic-level male rugby 7s athletes.

Methods:
In a double blind, crossover study, 12 males (age 23 ± 4 years; stature 1.85 ± 0.07 cm; body mass 91.0 ± 7.0 kg; sum of 7-sites 52.2 ± 12.0 mm; YoYo IR1 19.3 ± 1.0) completed a RSA test (3 x (6 x 15 m + 15 m, 20 s recovery between reps and 120 s between series)) preceded 90 minutes by IPC treatment (4 x 5 min on/off at 220 mmHg bilateral leg occlusion) or Sham (4 x 5 min on/off at 20 mmHg bilateral leg occlusion).

Results:
No difference was found between the IPC and sham fastest or slowest sprint times, or when compared across all 18 sprints, with no intervention-sprint time interaction effect (p > 0.05). The percentage decrement across the 18 sprints was not significantly different between IPC and Sham interventions (p > 0.05). The accumulated four intervention pressure periods for ∆TSI% and ∆HHb were significantly greater in a negative and positive direction respectively for IPC compared with sham (p < 0.05).

Conclusion:
IPC did not negatively affect repeated sprint performance in elite male rugby 7s athletes. Peripheral oxygenation does not appear to be a limiting factor for RSA in elite male rugby 7s athletes.

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Aim:
The aim of this study was to assess the effects of cold-water immersion (cryotherapy) on indices of muscle damage following a bout of prolonged intermittent exercise.

Methods:
Twenty males (mean age 22.3 years, s=3.3; height 1.80 m, s=0.05; body mass 83.7 kg, s=11.9) completed a 90-min intermittent shuttle run previously shown to result in marked muscle damage and soreness. After exercise, participants were randomly assigned to either 10 min cold-water immersion (mean 100C, s=0.5) or a non-immersion control group. Ratings of perceived soreness, changes in muscular function and efflux of intracellular proteins were monitored before exercise, during treatment, and at regular intervals up to 7 days post exercise.

Results:
Exercise resulted in severe muscle soreness, temporary muscular dysfunction, and elevated serum markers of muscle damage, all peaking within 48 h after exercise. Cryotherapy administered immediately after exercise reduced muscle soreness at 1, 24, and 48 h (P<0.05). Decrements in isometric maximal voluntary contraction of the knee flexors were reduced after cryotherapy treatment at 24 (mean 12%, sx=4) and 48 h (mean 3%, sx=3) compared with the control group (mean 21%, sx=5 and mean 14%, sx=5 respectively; (P<0.05).

Discussion:
Exercise-induced increases in serum myoglobin concentration and creatine kinase activity peaked at 1 and 24 h, respectively (P<0.05). Cryotherapy had no effect on the creatine kinase response, but reduced myoglobin 1 h after exercise (P<0.05).

Conclusion:
IPC did not negatively affect repeated sprint performance in elite male rugby 7s athletes. Peripheral oxygenation does not appear to be a limiting factor for RSA in elite male rugby 7s athletes.

View on ResearchGate