The effects of ischemic preconditioning on aerobic and anaerobic variables associated with submaximal cycling performance

Abstract

Acute limb ischemia induced by pressure cuffs before activity (ischemic preconditioning; IPC) has been reported to improve exercise performance at maximal efforts. The purpose of this investigation was to determine the effects of IPC during a submaximal performance test in competitive amateur level cyclists. Twelve healthy, male cyclists participated in two performance tests in which they cycled at successive relative intensities of 30, 50, and 70% of their maximal power output for 5 min each. The test culminated with an intensity of 90% of their maximal power output until exhaustion. Prior to each test, subjects randomly completed a control (CON) or IPC treatment. The IPC treatment consisted of alternating 220 mmHg of pressure applied by a cuff to the proximal portion of both thighs for 3, 5 min bouts separated by 5 min of rest. In addition to performance time to exhaustion, variables associated with aerobic performance (oxygen consumption, ventilation, respiratory exchange ratio, heart rate, and blood lactate) were measured continuously throughout the performance test. Statistical comparisons of data were made with repeated measures analyses of variance or paired T tests and significance was accepted as P < 0.05. Heart rate at the 30% relative intensity was significantly higher for the IPC treatment, but there were no other statistically significant differences between the control and IPC treatments across all variables and relative intensities. In this group of competitive amateur-level cyclists, an acute treatment of IPC did not improve performance at each submaximal intensity or increase time to exhaustion.

Ischemic preconditioning: Potential impact on exercise performance and underlying mechanisms

“…Similarly, IPC improved peak power output during maximal incremental leg cycling 10,13) . By contrast, other studies reported no effect of IPC on exhaustion time during maximal incremental leg cycling 14) , constant load leg cycling at an intensity of 130% of the peak power output 10) , the time needed to cycle 100 kJ of total work 15) . Additionally, IPC did not show any beneficial effects on increasing the maximal power output during maximal incremental leg cycling 16) .…”

“…Likewise, the heart rate peak (HRpeak) was not increased with IPC during maximal incremental leg cycling 13) , during constant load leg cycling until exhaustion 11,12) , maximal HR during a 5 km running time trial 21) , and 100 m swimming 19) . Additionally, maximum pulmonary ventilation (V ・ Emax) during maximal incremental leg cycling 13,14) was not affected by IPC.…”

“…As mentioned previously, the results are equivocal. Several studies found an improvement in exercise performance, i.e., time to failure (time trial performance), peak power output, and repetitions, to name a few, after IPC on the primary or a part of the engaged limbs 4,8,[10][11][12][13][18][19][20][21]26) , whereas other studies did not show any beneficial effects [5][6][7]9,10,[14][15][16][17]22,24,25) . A few studies investigated the effects of remote IPC on exercise performance.…”

“…IPC had no beneficial effects on the mean V ・ O2, V ・ E, and HR during a 5 km running time trial 22) , the submaximal V ・ O2 during maximal incremental leg cycling 13,14) , or during leg cycling at an exercise intensity of 90% V ・ O2peak at the gas exchange threshold 12) . However, IPC decreased LA at the submaximal running speed compared to SHAM 21) .…”

“…IPC also resulted in increases in HRmax and V ・ Epeak during maximal incremental leg cycling exercise 10) . Because the peak values of blood lactate concentration (LApeak) after exercise may be an indicator of anaerobic capacity, several studies compared the LApeak between IPC and the control (or SHAM), and no effect in LApeak after exercise with IPC was found 4,[9][10][11][12][13][14]18,19,22) . Two studies focused on muscle activity, assessed by electromyography (EMG), between IPC and CON, and no differences in EMG were found during cycle sprints 4) or isometric leg extension 26) .…”