Substrate utilization during arm and leg exercise relative to the ventilatory threshold in men.
ABSTRACT The purpose of this study was to determine variations in substrate utilization in men during arm and leg exercise at 70 and 90% of mode specific ventilatory threshold (Tvent).
Ten males served as subjects. Limb total and muscle volumes were estimated in the right arm and leg with anthropometry. Ventilatory equivalence, excess CO2, and modified V-slope methods were used to determine Tvent. Subjects performed 15 min of exercise at 70 and 90%Tvent arm cranking (AC) exercise, and 70 and 90%Tvent leg cycling (LC) exercise.
VO2, VE, and HR were higher during LC exercise at both intensities. However, arm and leg RPE were not different at 70 and 90%Tvent. There were no significant differences between modes at 70%Tvent in relative carbohydrate use (54.5+/-9.5 and 57.8+/-8.2% for AC and LC, respectively) and relative fat oxidation (45.5+/-9.5 and 42.2+/-8.2% for AC and LC, respectively). However, at 90%Tvent, relative carbohydrate oxidation was significantly higher during AC versus LC exercise (75.4+/-10.6 versus 68.6+/-9.0%, p<0.05). Energy expenditure (total kJ x min(-1) was significantly lower during AC exercise (14.5+/-2.9 and 18.4+/-3.4 for the 70 and 90%Tvent, respectively) versus LC exercise (27.1+/-3.3 and 34.8+/-4.1 for the 70 and 90%Tvent, respectively; p<0.05).
These results indicate that substrate use during AC exercise is similar to LC exercise at 70%Tvent. However, as the exercise intensity increases, the smaller arm musculature becomes more dependent on carbohydrate utilization compared to the legs.
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ABSTRACT: To compare fuel selection during prolonged arm (AE) and leg exercise (LE) with water or glucose ingestion. Ten subjects (VO2max: 4.77 +/- 0.20 and 3.36 +/- 0.15 L x min(-1) for LE and AE, respectively) completed 120 min of LE and AE at 50% of the mode-specific maximal power output (353 +/- 18 and 160 +/- 9 W, respectively) with ingestion of water (20 mL x kg(-1)) or 13C-glucose (2 g x kg(-1)). Substrate oxidation was measured using indirect respiratory calorimetry corrected for urea excretion and 13CO2 production at the mouth. The contribution of protein oxidation to the energy yield (%En) was higher during AE than LE (approximately 8% vs approximately 4%) because of the lower energy expenditure and was not significantly modified with glucose ingestion. With water ingestion, the %En from CHO oxidation was not significantly different during LE and AE (64 +/- 2% and 66 +/- 2%, respectively). Glucose ingestion significantly increased the %En from total CHO oxidation during AE (78 +/- 3%) but not during LE (71 +/- 2%). Exogenous glucose oxidation was not significantly different in AE and LE (56 +/- 4 and 65 +/- 3 g, respectively), but the %En from exogenous glucose was higher during AE than LE (30 +/- 1% and 24 +/- 1%) because of the lower energy expenditure. When glucose was ingested, the %En from endogenous CHO oxidation was significantly reduced during both AE (66 +/- 2% to 48 +/- 3%) and LE (64 +/- 2% to 47 +/- 3%) and was not significantly different in the two modes of exercise. The difference in fuel selection between AE and LE when water was ingested was modest with a slightly higher reliance on CHO oxidation during AE. The amount of exogenous glucose oxidized was lower but its %En was higher during AE because of the lower energy expenditure.Medicine and science in sports and exercise 11/2009; 41(12):2151-7. · 4.48 Impact Factor
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ABSTRACT: Energy expenditure (EE) and fat oxidation in handbike cycling compared to cycling in order to determine the intensity that elicits maximal fat oxidation in handbike cycling. To establish the exercise intensity with the highest fat oxidation rate in handbike cycling compared with cycling (control group) in order to give training recommendations for spinal cord-injured (SCI) athletes performing handbike cycling. Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. Eight endurance-trained handbike cyclists (VO2 peak(handbike cycling) 37.5+/-7.8 ml/kg/min) and eight endurance trained cyclists (VO2 peak(cycling) 62.5+/-4.5 ml/kg/min) performed three 20-min exercise blocks at 55, 65 and 75% VO2 peak in handbike cycling on a treadmill or in cycling on a cycling ergometer, respectively, in order to find the intensity with the absolutely highest fat oxidation. The contribution of fat to total EE was highest (39.1+/-16.3% EE) at 55% VO2 peak in handbike cycling compared to cycling, where highest contribution of fat to EE (50.8+/-13.8%) was found at 75% VO2 peak. In handbike cycling, the highest absolute fat oxidation (0.28+/-0.10 g/min) was found at 55% VO2 peak compared to cycling, where highest fat oxidation (0.67+/-0.20 g/min) was found at 75% VO2 peak. Well-trained handbike cyclists have their highest fat oxidation at 55% VO2 peak(handbike cycling) compared to well-trained cyclists at 75% VO2 peak(cycling). Handbike cyclists should perform endurance exercise training at 55% VO2 peak(handbike cycling), whereas well-trained cyclists should be able to exercise at 75% VO2 peak(cycling). For training recommendations, the heart rate at 55% VO2 peak(handbike cycling) lies at 135+/-6 bpm in handbike cycling in SCI compared to 147+/-14 bpm at 75% VO2 peak(cycling) in well-trained cyclists. We presume that the reduced muscle mass involved in exercise during handbike cycling is the most important factor for impaired fat oxidation compared to cycling. But also other factors as fitness level and haemodynamic differences should be considered. Our results are only applicable to well-trained handbike cyclists with SCI and not for the general SCI population.Spinal Cord 11/2004; 42(10):564-72. · 1.90 Impact Factor
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ABSTRACT: The aim of the present study was to compare arm and leg anaerobic peak and mean power after normalisation for body mass (W/kg) and fat-free mass (W/kg FFM) of 12 female and 10 male wrestlers, members of the Polish Olympic team. Power outputs were assessed by 30 seconds leg cycling and 30 seconds arm cranking. It was determined that males had higher peak power (11.4 W/kg and 13.2 W/kg FFM for legs, 9.6 W/kg and 11.2 W/kg FFM for arms) as well as mean power (8.7 W/kg and 9.6 W/kg FFM for legs, 6.9 W/kg and 7.9 W/kg FFM for arms) than females (peak power 8.6 W/kg and 11.3 W/kg FFM for legs, and 5.9 W/kg, 7.8 W/kg FFM for arms, mean power 6.8 W/kg, 9.0 W/kg FFM for legs and 5.9 W/kg, 7.8 W/kg FFM for arms). Post-exercise maximal blood lactate concentration after 30 seconds leg cycling and 30 seconds arm cranking was also higher in male wrestlers (11.9 and 11.8 mmol/l, respectively) than in female wrestlers (10.4 and 9.1 mmol/l, respectively). However the ratios of lactate concentration to mean power expressed in W/kg FFM for males and females in leg cycling (1.18 and 1.17, respectively) and in arm cranking (1.48 and 1.50, respectively) were similar. These findings suggest that the amount of energy derived from glycolysis is not sex-dependent. Additionally it seems that the higher ratios for arms when compared to legs reflect closer relation of arm muscle energy metabolism to carbohydrate utilisation.Journal of Science and Medicine in Sport 01/2005; 7(4):473-80. · 2.90 Impact Factor