Is the balance between skeletal muscular metabolic capacity and oxygen supply capacity the same in endurance trained and untrained subjects?

Abstract

We attempted to test whether the balance between muscular metabolic capacity and oxygen supply capacity in endurance-trained athletes (ET) differs from that in a control group of normal physically active subjects by using exercises with different muscle masses. Methods:We compared maximal exercise in 9 ET subjects (Maximal oxygen uptake [VO 2 max] 64 ml·kg -1 ·min -1  SD 4) and 8 controls (VO 2 max 464 ml·kg -1 ·min -1 ) during one-legged knee extensions (1-KE), two-legged knee extensions (2-KE) and bicycling. Maximal values for power output (P), VO 2 max, concentration of blood lactate ([La -]), ventilation (VE), heart rate (HR), and arterial oxygen saturation of haemoglobin (SpO 2 ) were registered. Results: P was 43 (2), 89 (3) and 298 (7) W (mean  SE); and VO 2 max: 1387 (80), 2234, (113) and 4115 (150) ml·min -1 ) for controls in 1-KE, 2-KE and bicycling, respectively. The ET subjects achieved 126%, 121% and 126% of the P of controls (p<0.05) and 127%, 124% and 117% of their VO 2 max (p<0.05). HR and [La -] were similar for both groups during all modes of exercise, while VE in ET was 147% and 114% of controls during 1-KE and bicycling, respectively. For mass-specific VO 2 max (VO 2 max divided by the calculated active muscle mass) during the different exercises, ET achieved 148%, 141% and 150% of the controls' values, respectively (p<0.05). During bicycling, both groups achieved 37% of their massspecific VO 2 during 1-KE. Conclusion: ET subjects have the same utilization of the muscular metabolic capacity during whole body exercise as active control subjects.2

One‐legged endurance training: leg blood flow and oxygen extraction during cycling exercise

“…This increase in blood flow is a consequence of an increase in local vascular conductance, albeit muscle blood flow is balanced by sympathetic vasoconstrictor activity during whole-body exercise (Secher et al 1977, Volianitis & Secher 2002, Mortensen et al 2005, Rud & Hallen 2009. Both muscle oxidative capacity and one-legged VO 2 max were increased by one-legged endurance training in endurance-trained subjects, without affecting their VO 2 max for cycling.…”

“…Hence, training-induced increase in muscular oxidative capacity affects both oxygen delivery and extraction and During exercise, muscle perfusion increases with intensity to suffice the oxygen demand. This increase in blood flow is a consequence of an increase in local vascular conductance, albeit muscle blood flow is balanced by sympathetic vasoconstrictor activity during whole-body exercise (Secher et al 1977, Volianitis & Secher 2002, Mortensen et al 2005, Rud & Hallen 2009. Accordingly, at high exercise intensities, when a maximal cardiac output is approached, the increase in blood flow to the exercising muscles is restricted and the increase in oxygen uptake per unit of developed power attenuated.…”

“…During whole-body exercise, however, limited venous return to the heart and hence cardiac output provoke peripheral vasoconstriction that implicates muscle blood flow and oxygen uptake (Secher et al 1977, Volianitis & Secher 2002, Mortensen et al 2005. For example, in both endurance-trained and untrained subjects, leg oxygen uptake during cycling is lower than 50% of the capacity of the leg as revealed during one-legged knee extension exercise (Rud & Hallen 2009). That is the case because the arterial baroreceptors secure arterial blood pressure at the expense of flow to working skeletal muscles (Collins et al 2001, Ogoh et al 2003.…”

The Influence of Cold Therapy on the Physical Working Capacity at the Electromyographic Threshold for Consecutive Exercise Sessions

“…Moreover, studies indicate that the oxygen consumption of the working muscles (i.e., quadriceps femoris) at maximal exercise for the single-leg knee-extensor ergometer are approximately two to three times higher than the oxygen consumption for the same muscles during cycle ergometry [ 33 , 34 , 35 ]. For example, Ru and Hallén [ 36 ] reported that mass-specific oxygen uptake (i.e., dividing the net oxygen uptake by the active muscle mass during exercise) was significantly higher for single-leg knee-extensor ergometer versus cycle ergometry (~0.400 vs. ~0.015 L of oxygen per kg of muscle mass per min). In addition, studies have compared the EMG amplitude for the quadriceps femoris muscles, using incremental testing, between the two exercise modalities (single-leg cycle ergometry and single-leg knee-extensor ergometer) and found that the EMG amplitude is ~40% higher at maximal exercise for single-leg knee-extensor ergometer versus single-leg cycle ergometry [ 37 ].…”