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High-intensity intermittent cycling increases purine loss compared with workload-matched continuous moderate intensity cycling.

Gerber T, Borg ML, Hayes A, Stathis CG - Eur. J. Appl. Physiol. (2014)

Bottom Line: Despite a lower estimated work performed; high-intensity intermittent exercise (HIIE) training produces greater fat mass reductions when compared with workload-matched continuous (CON) steady state exercise.Exercise-induced plasma Hx accumulation and urinary purine excretion are greater following HIIE and indirectly represents a net loss of adenosine triphosphate (ATP) from the muscle.The subsequent restorative processes required for intramuscular de novo replacement of ATP may contribute to a negative energy balance and in part, account for the potential accelerated fat loss observed with HIIE when compared with CON training programs.

View Article: PubMed Central - PubMed

Affiliation: College of Health and Biomedicine, Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia.

ABSTRACT

Purpose: Exercise at 50-60 % of peak oxygen consumption (VO2 peak) stimulates maximal fat oxidation rates. Despite a lower estimated work performed; high-intensity intermittent exercise (HIIE) training produces greater fat mass reductions when compared with workload-matched continuous (CON) steady state exercise. No metabolic basis has been documented nor mechanisms offered to explain this anomaly. This study investigated the physiological and metabolic responses of two different workload-matched exercise protocols.

Methods: On separate occasions and at least 1 week apart, eight apparently healthy males cycled for 30 min at either 50 % VO2 peak (CON) or performed repeated 20 s bouts of supramaximal exercise at 150 %VO2 peak separated by 40 s rest (HIIE).

Results: The average heart rate, oxygen consumption, plasma glycerol and free fatty acid concentrations were not different during exercise and recovery between the trials. Plasma lactate and hypoxanthine (Hx) concentrations were elevated and urinary excretion rates of Hx and uric acid were greater following HIIE as compared to CON (P < 0.05).

Conclusion: Exercise-induced plasma Hx accumulation and urinary purine excretion are greater following HIIE and indirectly represents a net loss of adenosine triphosphate (ATP) from the muscle. The subsequent restorative processes required for intramuscular de novo replacement of ATP may contribute to a negative energy balance and in part, account for the potential accelerated fat loss observed with HIIE when compared with CON training programs.

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Purine metabolites during CON and HIIE exercise. Plasma uric acid (a) and plasma hypoxanthine (c) during exercise and recovery from CON and HIIE. Urinary uric acid excretion rate (b) and urinary hypoxanthine excretion rate (d) during resting (before exercise), and the recovery period (period including 30 min exercise and 60 min recovery). Data are mean ± SEM. *P < 0.05 Different from basal a given time point, n = 8 per group. CON white circles/bars, HIIE blackcircles/bars. Grey box represents the recovery period
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Fig2: Purine metabolites during CON and HIIE exercise. Plasma uric acid (a) and plasma hypoxanthine (c) during exercise and recovery from CON and HIIE. Urinary uric acid excretion rate (b) and urinary hypoxanthine excretion rate (d) during resting (before exercise), and the recovery period (period including 30 min exercise and 60 min recovery). Data are mean ± SEM. *P < 0.05 Different from basal a given time point, n = 8 per group. CON white circles/bars, HIIE blackcircles/bars. Grey box represents the recovery period

Mentions: Plasma UA remained constant during the CON exercise and recovery (Fig. 2a). However, plasma UA was significantly elevated above baseline levels at 20 (P = 0.03), 30 (P = 0.01), and 60 min (P = 0.01) after HIIE exercise. Urinary UA excretion was increased postexercise in both trials, however, CON resulted in a threefold increase in excretion from basal (P = 0.03), while HIIE resulted in an eightfold increase (P < 0.0001) in excretion rates (Fig. 2b). Plasma Hx increased over time in the HIIE (P = 0.025) and was significantly different from CON (P = 0.04) at completion of exercise (Fig. 2c). Plasma Hx remained elevated above baseline levels for 20 min into recovery (Fig. 2c; P = 0.004). HIIE resulted in a 70-fold increase in the urinary excretion of Hx (P = 0.003) whilst remaining constant during the CON exercise trial (Fig. 2d).Fig. 2


High-intensity intermittent cycling increases purine loss compared with workload-matched continuous moderate intensity cycling.

Gerber T, Borg ML, Hayes A, Stathis CG - Eur. J. Appl. Physiol. (2014)

Purine metabolites during CON and HIIE exercise. Plasma uric acid (a) and plasma hypoxanthine (c) during exercise and recovery from CON and HIIE. Urinary uric acid excretion rate (b) and urinary hypoxanthine excretion rate (d) during resting (before exercise), and the recovery period (period including 30 min exercise and 60 min recovery). Data are mean ± SEM. *P < 0.05 Different from basal a given time point, n = 8 per group. CON white circles/bars, HIIE blackcircles/bars. Grey box represents the recovery period
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Related In: Results  -  Collection

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Fig2: Purine metabolites during CON and HIIE exercise. Plasma uric acid (a) and plasma hypoxanthine (c) during exercise and recovery from CON and HIIE. Urinary uric acid excretion rate (b) and urinary hypoxanthine excretion rate (d) during resting (before exercise), and the recovery period (period including 30 min exercise and 60 min recovery). Data are mean ± SEM. *P < 0.05 Different from basal a given time point, n = 8 per group. CON white circles/bars, HIIE blackcircles/bars. Grey box represents the recovery period
Mentions: Plasma UA remained constant during the CON exercise and recovery (Fig. 2a). However, plasma UA was significantly elevated above baseline levels at 20 (P = 0.03), 30 (P = 0.01), and 60 min (P = 0.01) after HIIE exercise. Urinary UA excretion was increased postexercise in both trials, however, CON resulted in a threefold increase in excretion from basal (P = 0.03), while HIIE resulted in an eightfold increase (P < 0.0001) in excretion rates (Fig. 2b). Plasma Hx increased over time in the HIIE (P = 0.025) and was significantly different from CON (P = 0.04) at completion of exercise (Fig. 2c). Plasma Hx remained elevated above baseline levels for 20 min into recovery (Fig. 2c; P = 0.004). HIIE resulted in a 70-fold increase in the urinary excretion of Hx (P = 0.003) whilst remaining constant during the CON exercise trial (Fig. 2d).Fig. 2

Bottom Line: Despite a lower estimated work performed; high-intensity intermittent exercise (HIIE) training produces greater fat mass reductions when compared with workload-matched continuous (CON) steady state exercise.Exercise-induced plasma Hx accumulation and urinary purine excretion are greater following HIIE and indirectly represents a net loss of adenosine triphosphate (ATP) from the muscle.The subsequent restorative processes required for intramuscular de novo replacement of ATP may contribute to a negative energy balance and in part, account for the potential accelerated fat loss observed with HIIE when compared with CON training programs.

View Article: PubMed Central - PubMed

Affiliation: College of Health and Biomedicine, Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia.

ABSTRACT

Purpose: Exercise at 50-60 % of peak oxygen consumption (VO2 peak) stimulates maximal fat oxidation rates. Despite a lower estimated work performed; high-intensity intermittent exercise (HIIE) training produces greater fat mass reductions when compared with workload-matched continuous (CON) steady state exercise. No metabolic basis has been documented nor mechanisms offered to explain this anomaly. This study investigated the physiological and metabolic responses of two different workload-matched exercise protocols.

Methods: On separate occasions and at least 1 week apart, eight apparently healthy males cycled for 30 min at either 50 % VO2 peak (CON) or performed repeated 20 s bouts of supramaximal exercise at 150 %VO2 peak separated by 40 s rest (HIIE).

Results: The average heart rate, oxygen consumption, plasma glycerol and free fatty acid concentrations were not different during exercise and recovery between the trials. Plasma lactate and hypoxanthine (Hx) concentrations were elevated and urinary excretion rates of Hx and uric acid were greater following HIIE as compared to CON (P < 0.05).

Conclusion: Exercise-induced plasma Hx accumulation and urinary purine excretion are greater following HIIE and indirectly represents a net loss of adenosine triphosphate (ATP) from the muscle. The subsequent restorative processes required for intramuscular de novo replacement of ATP may contribute to a negative energy balance and in part, account for the potential accelerated fat loss observed with HIIE when compared with CON training programs.

Show MeSH
Related in: MedlinePlus