Author(s): REYNOLDS, L., JONES, A.M., BOND, B.O., Institution: UNIVERSITY OF EXETER, Country: UNITED KINGDOM, Abstract-ID: 1669

INTRODUCTION:
Ischaemic preconditioning (IPC) refers to repeated brief periods of arterial occlusion and reperfusion and has recently gained attention due to its potential ergogenic effects. There is growing evidence that IPC applied remotely (to a non-exercising limb; RIPC) before exercise can improve performance. Prior severe-intensity exercise (exercise-based priming) has also been shown to enhance subsequent exercise tolerance (Bailey et al., 2009). However, the comparative magnitude of RIPC and priming, and whether combining these pre-exercise interventions provides an additive benefit to performance, remains unclear.
METHODS:
13 recreationally active adults (3 female) participated in the study (24+/-7 y, 1.81+/-0.07 m, 74+/-7 kg). In a randomised, repeated-measures design, participants completed a ramp test to determine maximal oxygen uptake (VO2max) and gas exchange threshold (GET), and four experimental conditions: CONTROL (no priming, no RIPC), RIPC, PRIME, and BOTH (RIPC and priming). We replicated an ergogenic priming protocol (Bailey et al., 2009) consisting of 6 min severe-intensity cycling at 70% of the difference between GET and VO2max (70% delta), followed by 20 min recovery. RIPC comprised two 5-min bouts of bilateral upper-arm occlusion applied in the 20 min period before the criterion exercise bout. The work-to-work cycling test involved 3 min at 20 W, 4 min at 90% GET, then 80% delta to exhaustion. Time to exhaustion (TTE) was the primary outcome. Pulmonary VO2, muscle oxygenation, EMG, and heart rate were measured continuously. Each condition was performed twice per participant so pulmonary VO2 and muscle oxygenation data could be ensemble averaged for kinetic analysis. Blood lactate concentration ([BLa]) and ratings of perceived exertion (RPE) were assessed at discrete time points during the test and at exhaustion.
RESULTS:
A one-way repeated-measures ANOVA showed a significant effect of condition on TTE (P=0.033, eta_p^2=0.213). TTE was higher in RIPC than CON (+29.7 s, 95% CI [-1.08, 60.48]), although this did not reach statistical significance (P=0.057), and was significantly greater in RIPC (+37.0 s, 95% CI [8.27, 65.73], P=0.016) and BOTH (+23.0 s, 95% CI [9.22, 36.78], P=0.003) compared with PRIME. PRIME and BOTH did not differ from CON (P>0.311). End-exercise VO2 and RPE did not differ between trials (P>0.05). [BLa] at exhaustion was significantly higher in RIPC vs PRIME (+1.02 mmol L-1, P=0.041, 95% CI [0.51, 1.98]).
CONCLUSION:
RIPC enhanced severe-intensity cycling tolerance. Combining RIPC and priming offered no additional benefit beyond RIPC alone. Future studies should explore the mechanisms underlying the effects of RIPC and priming, and whether different combinations and timings of these interventions can produce additive ergogenic effects.


Bailey, S. J., et al. (2009). Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance. JAP, 107(6), 1743-1756.