Heart Rate Recovery, Blood Pressure Recovery, and 24-hour Heart Rate among Firefighters

Abstract

The purpose of the present study was to examine the effects of 3 days isoenergetic high-fat/low-carbohydrate diet (HF-LC) relative to low-fat/high-carbohydrate diet (LF-HC) on the exercise-induced growth hormone (GH) response in healthy male subjects.Ten healthy young males participated in this study. Each subject consumed the HF-LC (18 ± 1% protein, 61 ± 2% fat, 21 ± 1% carbohydrate, 2720 kcal per day) for 3 consecutive days after consuming the LF-HC (18 ± 1% protein, 20 ± 1% fat, 62 ± 1% carbohydrate, 2755 kcal per day) for 3 consecutive days. After each dietary intervention period, the hormonal and metabolic responses to an acute exercise (30 min of continuous pedaling at 60% of V˙O2max) were compared. The intramyocellular lipid (IMCL) contents in the vastus lateralis, soleus, and tibialis anterior were evaluated by proton magnetic resonance spectroscopy.Serum GH concentrations increased significantly during the exercise after both the HF-LC and LF-HC periods (P < 0.05). However, the exercise-induced GH response was not significantly different between the two periods. Fat utilization and lipolytic responses during the exercise were enhanced significantly after the HF-LC period compared with the LF-HC period. IMCL content did not differ significantly in any portion of muscle after the dietary interventions.We could not show that short-term HF-LC consumption changed significantly exercise-induced GH response or IMCL content in healthy young males.