Influence of intensity fluctuation on exercise metabolism

This investigation was undertaken to examine the influence of intensity fluctuation on metabolic responses during and after exercise. Twenty-four males and 24 females were randomly assigned into one of the four groups consisting of 12 subjects of equal gender. Each group performed one of four 30-min exercise protocols: (1) cycling at a constant power output of 75 W (P1), (2) cycling with power output alternating between 50 and 100 W every 5 min (P2), (3) same as P2 except power output was alternated in a reverse order (P3), and (4) same as P2 except power output was alternated between 25 and 125 W (P4). Each exercise session was followed by a 25-min recovery and all protocols yielded the same mechanical work. Oxygen uptake (VO2), heart rate (HR), respiratory exchange ratio (RER), and plasma lactate concentrations ([La]) were measured at rest and during exercise and recovery. Ratings of perceived exertion (RPE) were recorded during exercise only. During exercise, VO2, HR and RPE did not differ across the four protocols. RER was higher (P < 0.05) in P4 than P1 and P2. [La] was higher (P < 0.05) in P4 than P1 and P3. During recovery, VO2 were lower (P < 0.05) in P1 than P2, P3, and P4, while [La] was higher in P4 than P3. When the total workload was equated, intensity fluctuation exerted no added effect upon metabolic responses during exercise, but provoked greater energy expenditure following exercise. Reversing the order or increasing the magnitude of intensity fluctuation would not further alter metabolic consequences.

[1]  D. Poole,et al.  The Slow Component of Oxygen Uptake Kinetics in Humans , 1996, Exercise and sport sciences reviews.

[2]  R. Withers,et al.  The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption , 2004, European Journal of Applied Physiology and Occupational Physiology.

[3]  C. Melby,et al.  Effect of exercise intensity and duration on postexercise energy expenditure. , 1989, Medicine and science in sports and exercise.

[4]  B G Denys,et al.  Effect of carbohydrate ingestion subsequent to carbohydrate supercompensation on endurance performance. , 1995, International journal of sport nutrition.

[5]  O. Wigertz,et al.  Physiological Correlates of Perceived Exertion in Continuous and Intermittent Exercise with the Same Average Power Output , 1972, European journal of clinical investigation.

[6]  G. Borg.  Perceived exertion as an indicator of somatic stress. , 2019, Scandinavian journal of rehabilitation medicine.

[7]  P. Raven,et al.  Effect of pedal rate on cardiorespiratory responses during continuous exercise. , 1992, Medicine and science in sports and exercise.

[8]  Nicholas A Ratamess,et al.  Metabolic and perceptual responses during Spinning cycle exercise. , 2005, Medicine and science in sports and exercise.

[9]  T D Noakes,et al.  Metabolic and performance responses to constant-load vs. variable-intensity exercise in trained cyclists. , 1999, Journal of applied physiology.

[10]  Bengt Saltin,et al.  Intermittent Exercise: its Physiology and some Practical Applications , 1976 .

[11]  P. Francis,et al.  Physiological Response to a Typical Studio Cycling Session , 1999 .

[12]  J. Goñi.  [Medicine and sports]. , 1991, Revista de medicina de la Universidad de Navarra.

[13]  W. Stainsby,et al.  Norepinephrine increases canine skeletal muscle VO2 during recovery. , 1982, Medicine and science in sports and exercise.

[14]  F. Nagle,et al.  Effect of work intensity and duration on recovery O2. , 1980, Journal of applied physiology: respiratory, environmental and exercise physiology.

[15]  G. Brooks,et al.  Metabolic bases of excess post-exercise oxygen consumption: a review. , 1984, Medicine and science in sports and exercise.

[16]  K. Metz,et al.  Metabolic efficiency during arm and leg exercise at the same relative intensities. , 1997, Medicine and science in sports and exercise.

[17]  S. Green,et al.  Effects of split exercise sessions on excess postexercise oxygen consumption and resting metabolic rate. , 1998, Canadian journal of applied physiology = Revue canadienne de physiologie appliquee.

[18]  P E Di Prampero,et al.  Energy utilization in intermittent exercise of supramaximal intensity. , 1969, Journal of applied physiology.

[19]  J A Faulkner,et al.  Temperature, skeletal muscle mitochondrial functions, and oxygen debt. , 1971, The American journal of physiology.

[20]  J. Kang,et al.  Effect of contraction frequency on energy expenditure and substrate utilisation during upper and lower body exercise , 2004, British Journal of Sports Medicine.