Author(s): DUFOUR, S.P.1, MAVROPALIAS, G.2,3, SCOTT, B.R.3, HASELER, L.4, NOSAKA, K.3, Institution: UNIVERSITY OF STRASBOURG, Country: FRANCE, Abstract-ID: 1586

INTRODUCTION:
Eccentric (ECC) cycling allows greater mechanical load to be achieved despite lower metabolic demand [1] and induces different acute cardiorespiratory and neuromuscular responses than those observed during conventional concentric (CON) cycling [2-3]. The present study aimed to determine how pedal cadence and blood flow restriction (BFR) to the exercising limb affect acute cardiorespiratory, vascular and neuromuscular responses to ECC cycling.
METHODS:
Healthy males (n=10, 38±10y, BMI 24.0±2.5) completed 4 sessions over 4-wk. The first two sessions were used to familiarize the participants to procedures including single leg (SL) ECC cycling, maximal voluntary knee extensor isometric strength (MVC) and microvascular function tests (MVF) based on vastus lateralis (VL) oxygenation response to 5-min arterial occlusion/reperfusion. In addition, SL-CON cycling sprint power for 10-s at 20- and 60-rpm were measured. The following two visits consisted of 15 bouts of 40-s SL-ECC cycling at 25% SL-CON sprint power, with 20-s passive cycling recovery. One leg cycled with BFR (60% of arterial occlusion pressure) while the other cycled without (non-BFR). Cardiorespiratory function (indirect calorimetry and telemetry), VL oxygenation (near infra-red spectroscopy) and electromyographic activity (EMG) were continuously recorded. Blood lactate (BL), MVC and MVF were assessed before and after exercise. Two-way repeated measures ANOVAs were performed to test for cadence and BFR effects on the measures. All data are expressed as mean ± SD and a significant level was set at p<0.05.
RESULTS:
Mean power output was higher (p<0.001) at 60- (133±23W) than 20-rpm (57±11W) without difference between BFR and non-BFR conditions. Oxygen uptake (+58%), heart rate (HR, +15%), pulmonary ventilation (+28%) and breathing rate (BR, +25%) were greater during exercise at 60-rpm than 20-rpm (p<0.05). VE (+20%) and BR (+13%) were higher (p<0.05) in the BFR than non-BFR condition, while HR tended to be higher (+6%, p=0.066) with BFR than non-BFR. VL oxygenation was 6% lower at 60- than 20-rpm and also reduced by 16% in BFR compared to non-BFR condition (cadence effect p<0.01, BFR effect p<0.001). Post-exercise BL was not significantly altered by cadence but was 38% higher (p<0.05) in the BFR than non-BFR condition. There was no significant cadence nor BFR effects on EMG activity, MVC and MVF tests.
CONCLUSION:
These data suggest greater acute cardiorespiratory and muscle metabolic challenges when ECC cycling is performed at faster pedal cadence with BFR. Therefore, combining faster pedal cadence and BFR might be a useful strategy to enhance cardiorespiratory and muscle metabolic training stimuli for future chronic studies exploring the functional benefits of ECC cycling in clinical and athletic populations.

1. Dufour et al. Am J Physiol Regul Integr Comp Physiol. 2007
2. Barreto et al. J Sports Med Phys Fitness. 2023
3. Isner-Horobeti et al. Sports Med. 2013

SD was supported by a grant from Region Grand Est, France