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The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25 ± 2 yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound, and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO2diff) during 6-min bouts of 60, 80, and 100% of maximal work rate (WRmax), respectively. Blood flow and oxygen uptake increased (P < 0.05) from 60%WRmax [557 ± 177(SD) ml/min; 56.0 ± 21.6 ml/min] to 80%WRmax (679 ± 190 ml/min; 70.6 ± 24.8 ml/min), but no change was seen from 80%WRmax to 100%WRmax. Blood velocity (49.5 ± 11.5 to 58.1 ± 11.6 cm/s) and brachial diameter (0.49 ± 0.05 to 0.50 ± 0.06 cm) showed concomitant increases (P < 0.05) with blood flow from 60% to 80%WRmax, whereas no differences were observed in a-vO2diff. Shear rate also increased (P < 0.05) from 60% (822 ± 196 s-1) to 80% (951 ± 234 s-1) of WRmax. The mean response time (MRT) was slower (P < 0.05) for blood flow (60%WRmax 50 ± 22 s; 80%WRmax 51 ± 20 s; 100%WRmax 51 ± 23 s) than a-vO2diff (60%WRmax 29 ± 9 s; 80%WRmax 29 ± 5 s; 100%WRmax 20 ± 5 s), but not different from oxygen uptake (60%WRmax 44 ± 25 s; 80%WRmax 43 ± 14 s; 100%WRmax 41 ± 32 s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WRmax and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations. [ABSTRACT FROM AUTHOR]

Study design:Cross-sectional single-subject design.Objectives:To determine whether leg vascular occlusion (LEVO) augment arm cycling (ACE) peak oxygen uptake in spinal cord-injured individuals.Setting:University Hospital, Norway.Methods:Fifteen individuals with C4 to T12 spinal cord injury (SCI) were recruited and divided into two groups: injury above (SCI-high, n=8) or below (SCI-low, n=7) the T6 level. Peak oxygen uptake (VO2peak) was measured during (1) ACE combined with LEVO, (2) ACE alone and (3) ACE combined with functional electrical stimulation cycling (FES hybrid cycling).Results:In the SCI-high group, VO2peak and peak Watt during ACE with LEVO were higher than ACE alone: 20.0 (±5.0) versus 17.6 (±5.0) ml kg−1 min−1 (P=0.006), and 72.5(±32) versus 80.0 (±34) Watt (P=0.016), respectively. However, FES hybrid cycling VO2peak was significantly higher than ACE with LEVO: 24.4 (±4.1) versus 20.0 (±5.0) ml kg−1 min−1 (P=0.006). In the SCI-low group, there was no difference in VO2peak and related parameters between the three modalities.Conclusions:For spinal cord-injured individuals with injury level above T6 (high) in the present study, LEVO combined with ACE augment VO2peak. However, this acute increase in VO2peak was lower than when FES cycling was combined with ACE. These findings may have future implications for exercise prescription for spinal cord-injured individuals. [ABSTRACT FROM AUTHOR]

This study sought to study the effect of high intensity aerobic interval endurance training on peak stroke volume and maximal strength training on mechanical effi ciency in coronary artery disease (CAD) patients. 8 CAD patients (age 61.4 ± 3.7 years) trained 30 interval training sessions with 4 × 4 min intervals at 85 - 95 % of peak heart rate while 10 CAD patients (age 66.5 ± 5.5 years) trained 24 sessions of maximal horizontal leg press. In the interval training group peak stroke volume increased significantly by 23 % from 94.1 ± 23.0 mL · beat ? 1 to 115.8 ± 22.4 mL · beat ? 1 (p < 0.05). Peak oxygen uptake increasedsignificantly by 17 % from 27.2 ± 4.5 mL · kg ? 1 · min ? 1 to 31.8 ± 5.0 mL · kg ? 1 min ? 1 (p < 0.05) in the same group. In contrast, there was no such exercise training-induced change in peak stroke volume or peak oxygen uptake in the maximalstrength training group, despite a 35 % improvement in sub maximal walking performance. [ABSTRACT FROM AUTHOR]

Purpose: The present study investigated the effect of maximal strength training on running economy (RE) at 70% of maximal oxygen consumption (V[spacing dot above]O2max) and time to exhaustion at maximal aerobic speed (MAS). Responses in one repetition maximum (1RM) and rate of force development (RFD) in half-squats, maximal oxygen consumption, RE, and time to exhaustion at MAS were examined. Methods: Seventeen well-trained (nine male and eight female) runners were randomly assigned into either an intervention or a control group. The intervention group (four males and four females) performed half-squats, four sets of four repetitions maximum, three times per week for 8 wk, as a supplement to their normal endurance training. The control group continued their normal endurance training during the same period. Results: The intervention manifested significant improvements in 1RM (33.2%), RFD (26.0%), RE (5.0%), and time to exhaustion at MAS (21.3%). No changes were found in V[spacing dot above]O2max or body weight. The control group exhibited no changes from pre to post values in any of the parameters. Conclusion: Maximal strength training for 8 wk improved RE and increased time to exhaustion at MAS among well-trained, long-distance runners, without change in maximal oxygen uptake or body weight. [ABSTRACT FROM AUTHOR]

PURPOSE:: The present study compared the effects of aerobic endurance training at different intensities and with different methods matched for total work and frequency. Responses in maximal oxygen uptake (V O2max), stroke volume of the heart (SV), blood volume, lactate threshold (LT), and running economy (CR) were examined. METHODS:: Forty healthy, nonsmoking, moderately trained male subjects were randomly assigned to one of four groups:1) long slow distance (70% maximal heart rate; HRmax); 2)lactate threshold (85% HRmax); 3) 15/15 interval running (15 s of running at 90-95% HRmax followed by 15 s of active resting at 70% HRmax); and 4) 4 x 4 min of interval running (4 min of running at 90-95% HRmax followed by 3 min of active resting at 70%HRmax). All four training protocols resulted in similar total oxygen consumption and were performed 3 d.wk for 8 wk. RESULTS:: High-intensity aerobic interval training resulted in significantly increased V O2max compared with long slow distance and lactate-threshold training intensities (P < 0.01). The percentage increases for the 15/15 and 4 x 4 min groups were 5.5 and 7.2%, respectively, reflecting increases in V O2max from 60.5 to 64.4 mL.kg.min and 55.5 to 60.4 mL.kg.min. SV increased significantly by approximately 10% after interval training (P < 0.05). CONCLUSIONS:: High-aerobic intensity endurance interval training is significantly more effective than performing the same total work at either lactate threshold or at 70% HRmax, in improving V O2max. The changes in V O2max correspond with changes in SV, indicating a close link between the two. [ABSTRACT FROM AUTHOR]