Cardiovascular effects of cadence and workload

Oxygen consumption, rate of perceived exertion and enjoyment in high-intensity interval eccentric cycling

The objectives of this article are to compare oxygen consumption (VO₂) and perceptual responses between continuous and interval eccentric cycling protocols in order to test the hypothesis that metabolic demand and enjoyment would be greater for interval than continuous eccentric cycling protocols. Eleven recreationally active men (n = 9) and women (32.6 ± 9.4 years) performed a concentric cycling test to determine peak power output (PPO) followed by five eccentric cycling protocols on separate occasions: continuous eccentric cycling at 60% of PPO for 20 min at 60 rpm (CONT_20@60%) and 13.2 min at 90 rpm (CONT_13@60%), 4 × 4 min at 75% of PPO with 2-min rest (INT_4×4@75%), 12 × 1 min at 100% of PPO with 1-min rest (INT_1×12@100%) and 10 × 1 min at 150% of PPO with 1-min rest (INT_1×10@150%). Gas exchange and power output were recorded continuously, and rate of perceived exertion (RPE) and enjoyment were assessed after each exercise. Total VO₂ including the rest periods was the greatest (p < 0.0001) during INT_1×10@150% (382 ± 73 ml kg^-1) and lowest (p < 0.0001) during CONT_13@60% (146 ± 27 ml kg^-1). Total VO₂ during INT_1×12@100% (312 ± 59 ml kg^-1) was greater (p < 0.0001) than CONT_20@60% (246 ± 63 ml kg^-1) and INT_4×4@75% (257 ± 42 ml kg^-1). RPE was greater (p < 0.0001) after INT_1×10@150% (17 ± 2) than other conditions, but perceived enjoyment was not significantly different between protocols. It was concluded that the interval protocols increased metabolic demand without increasing RPE and enjoyment. It appears that high-intensity interval protocols can be used in eccentric cycling prescription.

Effect of Cadence on Time Trial Performance in Recreational Female Cyclists

Graham, PL, Zoeller, RF, Jacobs, PL, and Whitehurst, MA. Effect of cadence on time trial performance in recreational female cyclists. J Strength Cond Res 32(6): 1739-1744, 2018-The impact of pedaling cadence on cycling performance remains unresolved especially in female cyclists. The purpose of this study was to determine the effect of cadence on time trial (TT) performance in recreational female cyclists. Ten recreational female cyclists volunteered to participate in this study. Subjects performed 3 exercise sessions: 1 to assess peak oxygen uptake (V[Combining Dot Above]O2peak) and 2 TTs. Cadence was randomly ordered and fixed for each TT (60 or 100 rpm), whereas power output (PO) was freely adjusted by the participant, as tolerated. Time trial time, heart rate (HR), blood lactate, PO, V[Combining Dot Above]O2, and ratings of perceived exertion were measured throughout the TTs. The major finding of this study was the significantly faster (p = 0.001) TT time during the 60-rpm condition (34:23 ± 4:21) vs. the 100-rpm condition (37:34 ± 5:53). Also the 60-rpm TT resulted in significant differences for HR (155.9 ± 3.97 vs. 161.2 ± 5.20 b·min, p = 0.04), gross efficiency, (21.1 ± 0.37 vs. 17.7 ± 0.85%, p < 0.001), and PO (147 ± 7.06 vs. 129 ± 10.62 W, p = 0.003). Thus, a slower cycling cadence was associated with greater mechanical efficiency and PO, resulting in significantly better performance in a TT. These results suggest that recreational female cyclists may benefit from adopting a low cadence during an 8-km TT.

Incremental exercise using progressive versus constant pedaling rates: a study in cardiac patients

PURPOSE

Cardiopulmonary exercise testing is widely used in clinical assessment and exercise prescription. However, significant differences in physiological responses can occur depending on testing protocol. The aim of this study was to evaluate the cardiopulmonary responses to different incremental cycle pedaling cadences in cardiac patients.

METHODS

Eleven men with coronary artery disease (CAD) and 12 men with chronic heart failure (CHF) performed 2 maximal cycle tests at constant cadence (60-70 rpm, at fixed cadence) and at progressive cadence. Peak values for oxygen uptake (V(O(2)peak)), workload (W(peak)), and heart rate (HR(peak)); ventilatory threshold (VT); and the oxygen uptake (VO2) per unit work rate (WR) increment (ΔV(O(2))/ΔWR) obtained using 2 protocols were determined.

RESULTS

V(O(2)peak) and W(peak), respectively, were higher during increasing cadence (INCR) compared with fixed cadence (FIX) protocol both in patients with CAD (32.7 ± 5.4 vs 28.1 ± 7.0 mL · kg(-1) · min(-1), P = .01; 214 ± 42 vs 150 ± 28 W, P = .001) and in patients with CHF (20.3 ± 7.4 vs 17.2 ± 5.5 mL · kg(-1) · min(-1), P = .006; 133 ± 45 vs 104 ± 33 W, P = .005). No differences were seen in HR(peak). Both in patients with CAD and in patients with CHF, V(O(2)) (21.7 ± 5.5 vs 16.8 ± 5.3 and 12.3 ± 7.4 vs 9.3 ± 2.8 mL · kg(-1) · min(-1)) and HR (114 ± 14 vs 98 ± 13 and 92 ± 17 vs 80 ± 17 bpm) at VT were significantly higher in INCR than in FIX protocol. No differences were seen in workload at VT. ΔV(O(2))/ΔWR during INCR protocol were higher in patients with CAD (13.4 ± 1.8 vs 9.5 ± 2.6 mL · kg(-1) · W(-1), P = .006) and patients with CHF (13.6 ± 4.1 vs 8.7 ± 1.9 mL · kg(-1) · W(-1), P = .006).

DISCUSSION

These findings indicate that in tests at fixed cadence, there occurs an earlier activation of the anaerobic mechanisms leading to a premature exhaustion before a cardiopulmonary endpoint has been achieved.