No abstract

The aim of this study was to determine if the diminished aerobic capacity of coronary artery disease male (CAD) patients is accompanied by an impaired skeletal muscle function compared to healthy control subjects. Thirteen CAD patients and 9 healthy subjects performed both a maximal laboratory exercise testing and an assessment of the peripheral skeletal muscle function on an isokinetic apparatus. The cardiorespiratory and mechanical parameters were measured at ventilatory threshold and at maximal effort during a maximal exercise testing. The peripheral skeletal muscle function of the quadriceps was assessed from the maximal voluntary isometric force (MVIF) and from the static endurance time (SET) at an intensity of 50 % of the MVIF. The CAD patients showed a diminished aerobic capacity compared to healthy control subjects at maximal effort (maximal VO(2) uptake: p < 0.0001, maximal ventilation: p < 0.01; maximal heart rate: p < 0.0001, maximal power: p < 0.001) but also at VT (VO(2) uptake VT: p < 0.0001, Power VT: p < 0.001). No difference was found on the MVIF (p < 0.90) between the CAD patients and the control subjects whereas the SET was lower in the CAD patients (p < 0.01). The CAD patients had a lower aerobic capacity and an impaired skeletal muscle endurance compared to healthy subjects.

No abstract

Abstract:The purpose of the present study was to determine whether there are any differences in power output (PO) and/or quadriceps muscle (Quad) activity between black African and Caucasian football players during a force-velocity (fv) exercise test, which consisted of performing maximal 6-s sprints against an increasing load. Each subject started the test with a load of 2 kg and then recovered for 5 min before repeating the same test with a load increased by 2 kg. When the pedal frequency did not exceed 130 rev·min -1 , the load was increased by only 1 kg. Each subject attained the load corresponding to his maximal power if an additional increase in load (+1 kg) induced a power decrease. Nine black Africans (mean age 24.2 ± 3.3 years) and nine Caucasians (24.7 ± 4.2 years) (matched for stature and aerobic fitness) participated in the fv exercise test. During the test, PO, blood lactate, and the quadriceps electromyography (EMG) root mean square (Quad RMS) were assessed. Higher blood lactate was observed in Caucasians than in black Africans for POs over the load range from 4 kg up to the maximal power. However, PO and Quad RMS values were similar in Caucasians and black Africans. They also had similar lean leg volume (LLV) and consequently produced similar PO/LLV and Quad RMS/LLV values. Overall, our results suggest that Caucasians and black Africans matched for stature, max , and training background have similar PO and Quad RMS values, but different blood lactate concentrations during brief, intermittent, intense exercise performed on a cycloergometer.

This study investigated the effects of prior exercise on performance during a subsequent force-velocity (FV) exercise test. After determination of the individual maximal aerobic power (MAP) during maximal graded exercise testing, fifteen trained male subjects (age: 25 +/- 3 y) were randomly assigned to perform the FV exercise test without prior exercise (NPE) or preceded by prior exercise (PE) (10 min at 60 % of MAP, followed after 1-min rest interval by four intervals of 30-s cycling at 100 % MAP with 15-s rest intervals, then 10 min recovery). Blood samples were drawn at rest, and then for each work load at the 3rd minute of recovery. Skin temperature (T (sk)) from the rectus femoris and heart rate (HR) were measured continuously during prior exercise, the FV test, and during the 5-min recovery period at the end of each FV test. The Root Mean Square (RMS) of the surface electromyogram (EMG) signals obtained from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) were calculated during each sprint for each FV test. The lactate increase for each load (deltaLa) during the FV test was significantly less following PE than NPE. However, the lactate concentration (La) was significantly higher in the FV test following PE than NPE. There was an improvement in power output during the first two sprints (2 and 4 kg) following PE compared to NPE. There was also a more pronounced decrease in VL, VM, and RF RMS in PE compared to NPE. Our results showed that the first few sprints may provide sufficient prior exercise for the FV test. The higher lactate concentration following PE than NPE, despite no difference in maximum power, suggests that a large lactate accumulation may not be detrimental to FV test performance. However, a greater lactate concentration and T(sk) may be associated with a decrease in RMS.