Role of exercise duration on metabolic adaptations in working muscle to short-term moderate-to-heavy aerobic-based cycle training

• Published in: European journal of applied physiology Vol. 113; no. 8; pp. 1965 - 1978
• Main Authors: Green, Howard J., Burnett, Margaret, Carter, Sherry, Jacobs, Ira, Ranney, Don, Smith, Ian, Tupling, Susan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2013; Springer Nature B.V
• Subjects: Adaptation, Physiological; Adenosine; Adenosine Diphosphate - metabolism; Adenosine Monophosphate - metabolism; Biomedical and Life Sciences; Biomedicine; Biosynthesis; Exercise; Glycogen - metabolism; Homeostasis; Human Physiology; Humans; Inosine Monophosphate - metabolism; Kinases; Lactic Acid - metabolism; Male; Metabolism; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiology; Occupational Medicine/Industrial Medicine; Original Article; Oxygen Consumption; Phosphocreatine - metabolism; Physical fitness; Physiology; Proteins; Sports Medicine; Time Factors; Young Adult; Substrate; Duration; Vastus lateralis; Metabolism; Intensity; Aerobic training
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-013-2621-z

This study aimed at investigating the relative roles of the duration versus intensity of exercise on the metabolic adaptations in vastus lateralis to short-term (10 day) aerobic-based cycle training. Healthy males with a peak aerobic power ( ) of 46.0 ± 2.0 ml kg −1  min −1 were assigned to either a 30-min ( n  = 7) or a 60-min ( n  = 8) duration performed at two different intensities (with order randomly assigned), namely moderate (M) and heavy (H), corresponding to 70 and 86 % , respectively. No change ( P  > 0.05) in was observed regardless of the training program. Based on the metabolic responses to prolonged exercise (60 % ), both M and H and 30 and 60 min protocols displayed less of a decrease ( P  < 0.05) in phosphocreatine (PCr) and glycogen (Glyc) and less of an increase ( P  < 0.05) in free adenosine diphosphate (ADP f ), free adenosine monophosphate (AMP f ), inosine monophosphate (IMP) and lactate (La). Training for 60 min compared with 30 min resulted in a greater protection ( P  < 0.05) of ADP f, AMP f , PCr and Glyc during exercise, effects that were not displayed between M and H. The reduction in both and RER ( P  < 0.05) observed during submaximal exercise did not depend on training program specifics. These findings indicate that in conjunction with our earlier study (Green et al., Eur J Appl Physiol, 2012b ), a threshold exists for duration rather than intensity of aerobic exercise to induce a greater training impact in reducing metabolic strain.