Ischemic preconditioning of the muscle improves maximal exercise performance but not maximal oxygen uptake in humans

Abstract

Brief episodes of nonlethal ischemia, commonly known as "ischemic preconditioning" (IP), are protective against cell injury induced by infarction. Moreover, muscle IP has been found capable of improving exercise performance. The aim of the study was the comparison of standard exercise performances carried out in normal conditions with those carried out following IP, achieved by brief muscle ischemia at rest (RIP) and after exercise (EIP). Seventeen physically active, healthy male subjects performed three incremental, randomly assigned maximal exercise tests on a cycle ergometer up to exhaustion. One was the reference (REF) test, whereas the others were performed after the RIP and EIP sessions. Total exercise time (TET), total work (TW), and maximal power output (W(max)), oxygen uptake (VO(2max)), and pulmonary ventilation (VE(max)) were assessed. Furthermore, impedance cardiography was used to measure maximal heart rate (HR(max)), stroke volume (SV(max)), and cardiac output (CO(max)). A subgroup of volunteers (n = 10) performed all-out tests to assess their anaerobic capacity. We found that both RIP and EIP protocols increased in a similar fashion TET, TW, W(max), VE(max), and HR(max) with respect to the REF test. In particular, W(max) increased by ∼ 4% in both preconditioning procedures. However, preconditioning sessions failed to increase traditionally measured variables such as VO(2max), SV(max,) CO(max), and anaerobic capacity(.) It was concluded that muscle IP improves performance without any difference between RIP and EIP procedures. The mechanism of this effect could be related to changes in fatigue perception.

Ischaemic preconditioning does not alter the determinants of endurance running performance in the heat

“…However, the mean difference of 0.4 km.h -1 , does not exceed our calculated typical error of 0.5 km.h -1 established during pilot across a series of similar studies under the same conditions, indicating that changes may not be meaningful. Crisafulli et al (2011) has highlighted a role for altered fatigue perception to explain enhanced performance following IP, after observing no differences in physiological parameters including V* O 2max , maximal stroke volume and maximal cardiac output. These data cannot support, or refute this, as testing occurred under different environmental conditions.…”

“…Of note, Crisafulli et al (2011) reported a 4% increase in maximal power output and a ~40 s increase in total exercise time during an incremental cycling test to exhaustion immediately following IP, whilst de Groot et al (2010) observed a 3% increase in V0 O 2max , alongside a 1.6% increase in maximal power output during incremental cycling. Few studies have considered endurance running, however Bailey, Jones, et al (2012) reported lower blood lactate concentration (mean difference -1.07 mMol.L -1 ) throughout an incremental submaximal running test, although no subsequent effect on maximum oxygen consumption (V" O 2max ) was observed.…”

“…In turn, such changes will serve to maintain the supply of oxygen and energy substrates, whilst removing metabolites during exercise. Collectively, these haemodynamic and/or metabolic ischaemic responses may present a more efficient muscular action, facilitating greater work to be completed for the same energy expenditure (Crisafulli et al 2011;Pang et al 1995). Clevidence et al (2012) speculated that IP appears to be effective when an ischaemic event is most likely and may require a minimum metabolic stress to be achieved during the exercise bout to be effective during exercise.…”

“…Clevidence et al (2012) speculated that IP appears to be effective when an ischaemic event is most likely and may require a minimum metabolic stress to be achieved during the exercise bout to be effective during exercise. Thus, extreme environmental conditions, higher intensity exercise (Crisafulli et al 2011) and/or activities such as running (Bailey, Jones, et al 2012) and swimming (Jean-St-Michel et al 2011), that elicit significant physiological strain, warrant investigation.…”

Postural Stability Induced by Supervised Physical Training may improve also Oxygen Cost of Exercise and Walking Capacity in Post-Menopause, Obese Women

“…Ergocomp EL 1200, Marquette, Italy) for ECG data, and to a mass spectrometer (mod. II-CPX Express, Medgraphics, USA) in order to obtain metabolic and respiratory data [28]. She underwent to a cycle-ergometer incremental test (20W every 3 min,) up to volitional exhaustion, followed by 5 min of recovery.…”