**2. Materials and Methods**

#### *2.1. Subjects*

The intervention was performed in accordance with the Declaration of Helsinki and was approved by the Institutional Review Board of Chang Gung Memorial Hospital in Taiwan. A total of 36 sedentary males who were nonsmokers, nonusers of medication/vitamins, and free of any cardiopulmonary/hematological risks were recruited from Chang Gung University, Taiwan. No subject had performed regular exercise (i.e., exercise frequency once per week, duration < 20 min) for at least 1 year before the experiment. All subjects provided informed consent after the experimental procedures were explained. These subjects were randomly divided into three groups: the concentric cycling training (CCT, *n* = 12), the eccentric cycling training (ECT, *n* = 12), and the control (CTL, *n* = 12) groups. All subjects arrived at the testing center at 9:00 AM to eliminate any possible circadian effect. Participants were instructed to fast for at least 8 h and to refrain from strenuous physical exercise for at least 48 h before sampling.

#### *2.2. Protocol and Interventions*

Both the CCT and ECT groups performed exercise regimens on a stationary bicycle ergometer (CCT: Corival 400, Lode; ECT: custom-built cycle ergometer) 5 times a week for 6 weeks. For comparison, the CTL group did not perform any exercise, but their physical activities and daily diet were carefully documented.

All subjects reported their daily activities and nutrition intakes via questionnaires throughout the experiment. The participants were instructed to refrain from extra regular exercise until the end of this study. Moreover, the compliance rates for all three interventions were 100%.

The graded exercise test (GXT) was performed 48 h before and after the intervention. Both the CCT and ECT groups had a 3 day familiarization program upon initiation of training. The exercise intensity was set at 20%, 30%, and 40% of the maximal workload (Wmax) on each day. The first week's intensity was set at 45% Wmax and progressively increased 5% Wmax per week until 70% Wmax was obtained in the sixth week. Each training session contained a 6-min warm-up phase (3 min at 0% and 3 min at 30% Wmax), 30-min training period and 6-min cool-down phase (3 min at 30% and 3 min at 0% Wmax) (Figure 1). The training groups were asked to record their daily activities and nutritional intake using the short form of the international physical activity questionnaire and a written diet record, respectively. Subjects were asked to refrain from regular extra exercise until the end of the study. The participant compliance rate was 100% throughout this study.

**Figure 1.** Design of the experiment and the training intensity of eccentric and concentric groups in each week. Wmax: the maximal workload of the first graded maximal exercise test.
