Abstract
PURPOSE:
There is little data examining single-leg high intensity interval cycle training in older adults. The purpose of this study was to investigate the physiological responses of healthy older adults to a high intensity interval session using either single-leg (SL) or double-leg (DL) cycling.
METHODS:
In a randomised crossover design, fifteen healthy older adults (age: 55 ± 8 y, height: 1.71 ± 0.07 m, body mass: 77.2 ± 11.9 kg, VO2max: 37.1 ± 10.0 mL.kg.min-1; mean ± SD) completed two high intensity interval cycling sessions using either DL or SL cycling. Participants completed ten 30-sec DL intervals interspersed with 60 sec passive recovery and twenty (ten with each leg) 30-sec SL intervals interspersed with 60 sec passive recovery. Impedance cardiography, blood pressure, muscle oxygenation and total haemoglobin concentration (near-infrared spectroscopy), oxygen consumption (indirect caliometry) and power output were measured throughout each trial.
RESULTS:
Relative to lower limb muscle mass used in each trial (kg; dual energy xray absorptiometry), SL cycling resulted in greater oxygen consumption (DL: 84 ± 20.8 mL.kg-1.min-1 and SL: 101 ± 11.2 mL.kg-1.min-1; p<0.01) compared with DL cycling while power output (DL: 6.29 ± 1.53 W.kg-1 and SL: 6.01 ± 1.48 W.kg-1) was not different between trials. Total haemoglobin concentration (DL: 9.75 ± 10.75 μM.cm.s-1 and SL: 14.09 ± 5.05 μM.cm.s-1) and tissue oxygenation index (DL: 65.79 ± 1.94% and SL: 66.72 ± 5.44%) and were not different between DL and SL cycling. Additionally, cardiac output (DL: 14.3 ± 3.2 L.min-1 and SL: 12.3 ± 2.7 L.min-1; p<0.01) was higher during DL compared with SL cycling while mean arterial pressure (DL: 107 ± 10 mmHg and SL: 103 ± 9 mmHg) was not different between trials.
CONCLUSIONS:
For a similar muscle blood volume and oxygenation, SL cycling resulted in greater muscle oxygen consumption. However, this did not translate to greater mechanical power of the muscles. These results indicate age-related skeletal muscle alterations could affect the training responses to SL and DL high intensity interval cycling.