Effect of Endurance and Strength Training on the Slow Component of Kinetics in Elderly Humans.

We compared the effects of 8 weeks of high intensity, aerobic interval training ( and isoinertial resistance training ( on: (i) kinetics during heavy () intensity exercise and; (ii) work economy during moderate () intensity exercise in 12 healthy elderly men (69.3 ± 4.2 years). Breath-by-breath and muscle deoxygenation ([] by means of ) were measured in and at identical workloads before and after trainings. In , and responses were modeled as tri-exponential and mono-exponential increasing functions, respectively. A two-way ANOVA for repeated measures analysis was made; Effect size (η) was also evaluated. After the amplitude and the time delay of the slow component of uptake ( ) during were smaller (-32%; = 0.045) and longer (+19.5%; = 0.001), respectively. At : (i) during was lower (-5%; = 0.050); (ii) during , τ (+14.4%; = 0.050), (+8.6%; = 0.050), and τ (+17.2%; = 0.050) were longer than at . After , the decrease of the amplitude was likely induced by the beneficial effects of training on a more responsive delivery and consumption cascade leading to a better muscle metabolic stability. training was able to increase exercise economy during and to reduce the amplitude and delay the onset of during . These effects should be due to the reduction and the delayed recruitment of Type II muscle fibers. The better exercise economy and the delayed appearance of induced by suggests that strength training might be included in endurance training programs to improve exercise economy and resistance to fatigue in this population of old subjects.