Effect of selected recovery conditions on performance of repeated bouts of intermittent cycling separated by 24 hours.

The purpose of this study was to examine the effects of active recovery (AR), massage (MR), and cold water immersion (CR) on performance of repeated bouts of high-intensity cycling separated by 24 hours. For each recovery condition, subjects were asked to take part in 2 intermittent cycling sessions; 18 minutes of varying work intervals performed in succession at a resistance of 80 g/kg body weight separated by 24 hours. One of four 15-minute recovery conditions immediately followed the first session and included: (a) AR, cycling at 30% Vo(2)max; (b) CR, immersion of legs in a 15 degrees C water bath; (c) MR, massage of the legs; and (d) control, seated rest. Only the control condition showed a significant decline in the total work completed between the first and second exercise sessions (108.1 +/- 5.4 kJ vs. 106.0 +/- 5.0 kJ, p < 0.05). Thus, AR, MR, and CR appeared to facilitate the recovery process between 2 high-intensity, intermittent exercise sessions separated by 24 hours.

The relationships between aerobic fitness, power maintenance and oxygen consumption during intense intermittent exercise.

This study examined the relationships between VO2max, power maintenance and oxygen consumption during intense intermittent work. Female recreational soccer players were assigned to either a low aerobic power group (LOW, n = 6, mean (SD) VO2max = 34.4 (2.4) mL.kg(-1)min(-1) or to a moderate aerobic power group (MOD, n = 7, VO2max = 47.6 (3.8) mL.kg(-1).min(-1)). VO2 was measured while subjects performed 10 6-s all-out sprints (30-s passive recovery) on a Monark cycle ergometer. LOW and MOD subjects generated similar peak 6-s power (p = .58) but MOD had a smaller decrement in power (% DO) over the 10 sprints (LOW vs MOD: 18.0 (7.6) vs 8.8 (3.7) % DO, p = .02). The MOD group also consumed significantly more oxygen than LOW in 9 of the 10 sprint-recovery cycles (p < .05). Significant relationships were seen between VO2max and the aerobic response to the sprint-recovery series (r = .78, p =.002) as well as between VO2max and % DO (r = -.65, p = .02), while a non-significant relationship was seen between the oxygen consumed during the sprint-recovery cycles and % DO (r = -.41, p = .16). Thus, VO2max appears to be related to both an increased aerobic contribution to sprint-recovery bouts and the enhanced ability of the MOD group to resist fatigue during intense intermittent exercise.

The relationship between aerobic fitness and recovery from high intensity intermittent exercise.

A strong relationship between aerobic fitness and the aerobic response to repeated bouts of high intensity exercise has been established, suggesting that aerobic fitness is important in determining the magnitude of the oxidative response. The elevation of exercise oxygen consumption (VO2) is at least partially responsible for the larger fast component of excess post-exercise oxygen consumption (EPOC) seen in endurance-trained athletes following intense intermittent exercise. Replenishment of phosphocreatine (PCr) has been linked to both fast EPOC and power recovery in repeated efforts. Although 31P magnetic resonance spectroscopy studies appear to support a relationship between endurance training and PCr recovery following both submaximal work and repeated bouts of moderate intensity exercise, PCr resynthesis following single bouts of high intensity effort does not always correlate well with maximal oxygen consumption (VO2max). It appears that intense exercise involving larger muscle mass displays a stronger relationship between VO2max and PCr resynthesis than does intense exercise utilising small muscle mass. A strong relationship between power recovery and endurance fitness, as measured by the percentage VO2max corresponding to a blood lactate concentration of 4 mmol/L, has been demonstrated. The results from most studies examining power recovery and VO2max seem to suggest that endurance training and/or a higher VO2max results in superior power recovery across repeated bouts of high intensity intermittent exercise. Some studies have supported an association between aerobic fitness and lactate removal following high intensity exercise, whereas others have failed to confirm an association. Unfortunately, all studies have relied on measurements of blood lactate to reflect muscle lactate clearance, and different mathematical methods have been used for assessing blood lactate clearance, which may compromise conclusions on lactate removal. In summary, the literature suggests that aerobic fitness enhances recovery from high intensity intermittent exercise through increased aerobic response, improved lactate removal and enhanced PCr regeneration.

The relationship between aerobic fitness and both power output and subsequent recovery during maximal intermittent exercise.

The primary aim of the study was to establish a link between aerobic adaptation and both the recovery from maximal short duration exercise, and the ability to maintain power output in a subsequent bout. The question as to whether the aerobic adaptations facilitating recovery are centrally or peripherally located was also examined. Male university level rugby and soccer players (n=20) volunteered for the study. Mean (SD) age, mass and maximal oxygen uptake (VO2 max) was 21.9 (1.8) years, 84.7 (12.7) kg and 52.7 (6.9) ml x kg(-1) x min(-1) respectively. Subjects completed six 15s maximal intensity sprints (90s active recovery) on a Monark friction braked cycle ergometer. A significant relationship (r=-.49, P=0.03) was obtained between VO2 max (mL x kg(-1) x min(-1)) and the percent drop-off in mean power in bouts 5 and 6 compared with bout 1. A correlation of r=-.62 (P=0.002) was obtained between VO2 max (mL x kg(-1) x min(-1)) and the percent drop off in peak power in bouts 5 and 6 compared with bout 1. A significant correlation was obtained between arterial venous oxygen difference and the drop in mean power (r=-.54, P=0.02) but not with the drop in peak power (r=-.22, P=.36). There was no significant relationship between cardiac output and the drop in mean power (r=-.16, P=.51) or the drop in peak power (r=-.02, P=.94). Percent drop-off in oxygen consumption, when compared with the first, in the second (RVO2(30-60)), third (RVO2(60-90)), fourth (RVO2(90-120)) and fifth (RVO2(120-150)) 30s time periods of recovery following the intermittent protocol was calculated. Correlations between VO2 max (ml x kg(-1) x min(-1)) and these variables were (r=.51, P=-0.03), (r=.44, P=0.06), (r=.63, P=-0.003) and (r=.6, P=0.007) respectively. Consequently it was concluded that maximal oxygen uptake particularly the peripheral component, is an important determinant of the ability to perform intermittent exercise of this nature and to recover between bouts.

Altitude training for improvements in sea level performance. Is the scientific evidence of benefit?

Altitude training invokes physiological changes that are very similar to those caused by endurance training, As a result, it has been incorporated in the training regimes of elite athletes in an effort to improve sea level performance. Several training strategies, such as constant altitude exposure, intermittent altitude exposure or 'live high train low', have been used in an effort to incur an advantage in sea level performance over just sea level training alone. In spite of the accumulating scientific evidence that altitude training affords no advantage over sea level training, many coaches and athletes believe that it can enhance sea level performance for any athlete, whether endurance or power is the focus in their particular sport. However, altitude training may not be suitable for some athletes depending on their age, fitness level, health, iron status and the energy and technical requirements of their sport. The issue of whether altitude training enhances sea level performance remains a controversial topic.

The influence of a strength-sprint training sequence on multi-joint power output.

The purpose of this study was to determine whether adaptation to single- versus multi-joint strength training and sprint training was different and whether sequencing strength prior to sprint training was beneficial for increasing power. Thirty-two untrained males were assigned to control (C), sprint-sprint (SS), multi-joint (MJS), or single-joint (SJS) strength-sprint groups. Subjects were tested before training, after 8 wk of strength or sprint training, and after an additional 6 wk of sprint training. By mid-training both SJS and MJS increased 10 repetition maximum strength, but this was not transferable to isometric or isokinetic strength or rate of torque development. SS showed no improvement in these variables. All training groups increased cycle ergometer power output by 8 wk and had similar fiber hypertrophy with no EMG changes. Subsequent sprint training continued to increase maximum power with no further hypertrophy. Tibial nerve conduction velocity increased in all training groups. These results indicate little difference in adaptation to single- and multi-joint strength training. Strength or power improvements caused by training in these models does not transfer to isometric or isokinetic movements. Further, sequenced strength-spring training provided no additional power gain over sprint training alone.

Neuromuscular differences between volleyball players, middle distance runners and untrained controls.

Volleyball players, middle distance runners and non-athletes (n = 10/group) were tested to determine whether neuromuscular differences existed between groups and to clarify the roles of factors involved in maximal power production. The runners were leaner than controls, while the volleyball players were taller, heavier and had larger thigh volumes than the other groups. The volleyball players had higher absolute cycle ergometer power than both middle distance (26%) and control (15%) groups, but differences disappeared when expressed relative to body mass or thigh volume. Volleyball athletes were also stronger than both middle distance (51, 52%) and control subjects (33, 35%) for isokinetic leg extension and plantar flexion respectively (0-4.19 rad.s-1). In leg press they were stronger than middle distance (32%) and control subjects (36%) for only the isometric and 1.05 rad.s-1 contraction. The volleyball players also had higher rates of isometric torque development than the other groups, however nerve conduction velocity did not vary. Vastus lateralis biopsy samples revealed no differences in percent Type II muscle fibers, or fiber cross-sectional area between groups, yet volleyball athletes had larger Type II/I fiber area ratio than controls (15%). Both strength, rate of torque development and power were related to muscle and muscle fiber size variables, but not fiber distribution or nerve conduction velocity. The size of type II muscle fibers seemed to be especially important since this was the only variable related to power when adjusted for body size.

Reliability of measuring isometric and isokinetic peak torque, rate of torque development, integrated electromyography, and tibial nerve conduction velocity.

To determine the reliability of measures used in neuromuscular diagnosis and rehabilitation, 23 adults underwent identical testing on two occasions. Intraclass correlation coefficients (ICC) showed the reliability of peak torque measurement to depend both on the movement tested and velocity of contraction (leg extension ICC = 0.64-0.94, plantar flexion ICC = 0.55-0.76, leg press ICC = 0.72-0.91). Peak rate of torque development (RTD) and the percentage of peak torque at peak RTD were not reliable for any movement (ICC = 0.02-0.28). Mean RTD between 30% and 60% of peak torque was unreliable for leg press (ICC = 0.46), yet fairly reliable for both knee extension (ICC = 0.61) and plantar flexion (ICC = 0.63). Mean integrated electromyography (IEMG) showed fair to good reliability for isometric and 1.05 rad.s-1 leg press (ICC = 0.66, 0.90, respectively), and plantar flexion and leg extension (ICC = 0.75-0.89). Tibial nerve conduction velocity was highly reliable (ICC = 0.89). A range of reliabilities can be expected when measuring these variables, and must be considered when interpreting neuromuscular data.

Physiological predictors of short-course triathlon performance.

The purpose of this study was to investigate if selected physiological variables were related to triathlon performance. Eighteen male and seven female triathletes competed in a short-course triathlon (1-km swim, 30-km cycle, 9-km run) and underwent physiological testing within 14 d. VO2max and ventilatory threshold (VT) were measured on a cycle ergometer, treadmill, and tethered swim apparatus. Leg flexion and extension strength were measured on a Cybex II isokinetic dynamometer. Multiple linear regression did not improve the prediction of triathlon performance over that provided by simple correlations. Swim performance was related to relative swim VO2max in both males (r = -0.48) and females (r = -0.93) as well as the resistance pulled at swim VT (r = -0.81) and absolute leg flexion strength (r = -0.77) in females. No physiological variables were significantly related to cycling time in either gender. Running time was related to relative VO2max (r = -0.88) in females and velocity at run VT in both females (r = -0.88) and males (r = -0.73). Relative swim VO2max (r = -0.98), velocity at run VT (r = -0.89), and absolute leg flexion strength (r = -0.80) were related to overall performance in female triathletes. The only significant predictor of overall triathlon time for males was velocity at run VT (r = -0.78). It therefore appears that in short-course triathletes physiological variables in swimming and running are important to overall performance. Differences in sample size, group variability, and level of performance between males and females may account for the reported differences in the physiological predictors of performance between genders.

Physiological adaptations to velocity-controlled resistance training.

The force-velocity characteristics of skeletal muscle are such that maximal force is inversely related to the velocity of shortening. This relationship has been observed using isolated muscle preparations and intact muscle groups (e.g. knee extensors). Isokinetic dynamometry has revealed some specific physiological adaptations to different velocities of training: an increase in torque and power that are greater at or near the velocity of training; a transfer of torque gains to slower and faster angular velocities after intermediate velocity resistance training; increases in maximal oxygen consumption and cardiac output in response to circuit training; increases in anaerobic power output; changes in skeletal muscle size and changes in myofibrillar ATPase activity; and new applications for rehabilitation of muscular and ligamentous injuries, and post-coronary patients.

The influence of high-velocity circuit resistance training on VO2max and cardiac output.

In order to investigate the influence of high-velocity circuit resistance training on maximal aerobic power, maximal stroke volume and cardiac output, and blood lactate removal during recovery, 16 habitually active males were blocked on initial VO2max into either training or control groups. The training group completed two (weeks 1 and 2) or three (weeks 3-6) circuits of 10 variable-resistance hydraulic exercise stations at an exercise: relief ratio of 1:2 on alternate days over six weeks. Angular velocities of movement were maintained at approximately 3.1 rad.s-1. Following training, the VO2max was increased (p less than .01) from 4.32 to 4.68 1.min-1. Maximal stroke volume was increased (p less than .05) from 120 to 129 mL and heart rate response to an absolute submaximal exercise load was decreased (p less than .05) from 153 to 146 beats.min-1. As well, enhanced (p less than .01) removal of lactate from the blood was observed during recovery from exhausting exercise. No changes were observed for control subjects. These results indicate that positive alterations in aerobic and cardiovascular function may be achieved consequent to high-velocity circuit resistance training.

The effect of velocity-specific strength training on peak torque and anaerobic rowing power.

This study investigated the effect of low- and high-velocity resistance training on isokinetic peak torque and anaerobic power output. Eighteen male varsity oarsmen were blocked on peak knee extension torque at 3.14 rad s-1 and assigned to a high-velocity resistance training group (HVR), a low-velocity resistance training group (LVR) or a control group. Subjects trained four times a week for 5 weeks. Each training session included three circuits of 12 stations using variable-resistance hydraulic equipment. The HVR training significantly improved peak torque (P less than 0.05) in knee extension and flexion at 2.61, 3.14, 3.66 and 4.19 rad s-1. The LVR training produced significant improvements (P less than 0.05) in peak torque for knee extension and flexion at 0.52, 1.05, 1.57 and 2.61 rad s-1. High positive correlations were found between peak torque and anaerobic power outputs for all groups. However, no significant changes occurred in 15 s power output, average 90 s power output or peak blood lactate in either training group. These results indicate that velocity-specific strength training does not necessarily improve anaerobic power output in a different exercise mode despite the high positive correlation between isokinetic strength and anaerobic power output.

The influence of velocity-specific resistance training on the in vivo torque-velocity relationship and the cross-sectional area of quadriceps femoris.

This work was supported by Sport Canada end Hydra-Fitness Industries. In order to investigate the effects of velocity-specific resistance training, 30 healthy, male varsity athletes were assigned to either high (HVR) or low (LVR) velocity training or control (CG) groups. Subjects completed two 20-sec sets of maximal exercise at each of six hydraulic resistance stations for the lower limb. Resistances were adjusted as necessary to maintain consistent average angular velocities of approximately 1.05 and 3.14 rad/sec for the LVR and HVR groups, respectively. Subjects trained on alternate days for 6 weeks, completing either two (weeks 1 and 2) or three (weeks 3-6) circuits of the six stations each session. Peak knee extension torques were improved (p < 0.05) for the LVR group at all of seven angular velocities tested between 1.05 and 4.19 rad/sec. Improvements (p < 0.05) were also observed for the HVR group, but only at angular velocities of 2.62, 3.14, 3.66, and 4.19 rad/sec. Cross-sectional area of the quadriceps femoris muscle group obtained from serial computer tomography (CT) scans was increased (p < 0.05) for both training groups. No significant changes in either strength or cross-sectional area were observed for control subjects. These results indicate that while both of the training programs resulted in increased cross-sectional area of the knee extensors, the observed changes in strength performance are likely due to other factors which may be mediated by the different training velocities. J Orthop Sports Phys Ther 1989;10(11):456-462.

The effect of exercise duration on the exercise and post-exercise oxygen consumption.

This study was designed to determine the effect of duration (30, 45, 60 min) of exercise at 70% VO2 max on oxygen consumption during the exercise and post-exercise periods and if the post-exercise oxygen consumption (EPOC) is related to elevated tympanic temperature. Two male and three female volunteer subjects cycled at 70% VO2 max for 30, 45 and 60 min. The EPOC increased 2.35 and 5.3 fold when exercise duration was increased from 30 to 45 min and from 30 to 60 min respectively. The time for VO2 to return to resting levels following exercise was 128 +/- 4.4 min, 204 +/- 15.9 min and 455 +/- 30.0 min after the 30, 45 and 60 min exercise bouts. Tympanic temperatures were stable at 38.6 degrees C after approximately 30 min of exercise, but all had fallen to resting conditions approximately two hours post-exercise. The correlation between core temperature and EPOC, and RER and EPOC, was r = 0.64-0.75 and r = 0.86-0.89, respectively. These data emphasize the importance of extending the work time for elevating the energy cost during and post-exercise, and suggest that the EPOC can be explained in part by the effects of elevated temperature and metabolic substrate.

Sequencing of endurance and high-velocity strength training.

To compare two sequences of endurance (E) and high-velocity resistance (HVR) training, sixteen male oarsmen were separated into Group ES which trained endurance prior to strength and Group SE which trained strength prior to endurance. The endurance program consisted of up to 60 min a session, five days a week for five weeks. HVR exercise was conducted on 12 stations of variable resistance hydraulic equipment, four sessions per week for five weeks. Endurance training significantly improved VO2max and submaximal heart rate and blood lactate responses in both groups regardless of the sequence followed. HVR training improved VO2max in group SE only and had no effect on submaximal response to exercise. Peak torque increases for knee extension and flexion with HVR training were greater in group SE than group ES. These results show that organizing strength and endurance training into sequential programs can influence the physiological adaptation to training.

The influence of one-legged training on cardiorespiratory fitness.

Supported by University of Victoria Research Grant. The purpose of this investigation was to examine the influence of single leg training on one- and two-legged maximal oxygen consumption (VO2 max). Nine volunteers completed 7 weeks of one-legged interval training on a cycle ergometer adapted for single leg pedaling. The training regimen consisted of 15-20 intervals of 20 sec duration (1:3 work to rest ratio), 4 days a week at an intensity of 150% of the initial power output that elicited one-legged VO2 max. Pedaling cadence was maintained at 90 rpm. Heart rate (HR) was monitored throughout all training sessions. The results demonstrate that one-legged VO2 max was significantly increased (p < 0.05) from 3.36 l/min in the pretrained condition to 3.57 l/min and 3.69 l/min in the untrained (UT) and trained legs (T), respectively. No significant differences were observed between the UT and T legs for one-legged VO2 max after training. Two-legged VO2 max showed a 5% elevation following single leg training (p < 0.05). These data suggest that one-legged interval training of high intensity and short duration can improve both one- and two-legged maximal oxygen consumption. This finding implies that individuals can maintain aerobic power during rehabilitation following an injury to one limb, through the use of one-legged interval training on a cycle ergometer.J Orthop Sports Phys Ther 1988;10(1);8-11.

The influence of high-velocity resistance circuit training on aerobic power*.

* This work was supported by the Natural Sciences and Engineering Research Council. This study was designed to investigate the influence of high-velocity resistance circuit training on maximal aerobic power. Twenty-seven trained males participated either as training (N = 16) or control (N = 11) subjects. The training group exercised for two 20 sec sets at each of six stations of hydraulic, variable resistance apparatus over two or three circuits maintaining an exercise:relief ratio of 1:2 during each circuit. Subjects trained four times weekly over 5 weeks. The resistance at each station was adjusted as necessary to maintain consistent angular limb velocities of approximately 3.2 rad/sec. The VO2max for the training group was increased (p < 0.001) by 9.5% when expressed in either absolute or relative terms. No changes were observed for control subjects. Oxygen consumption responses measured over two circuits for six training group subjects averaged 61 and 57% of VO2max for exercise and relief intervals, respectively. It is therefore suggested that the hydraulic circuit resistance program described will elicit a metabolic intensity sufficient to improve aerobic power, even in previously trained subjects.J Ortho Sports Phys Ther 1988;9(10):339-344.

The effect of one-legged sprint training on intramuscular pH and nonbicarbonate buffering capacity.

To determine the effect of one-legged sprint training on muscle pH and nonbicarbonate buffering capacity (BC), 9 subjects completed 15 to 20 intervals at 90 RPM, 4 days a week for 7 weeks on a bicycle ergometer adapted for one-legged pedaling. Needle biopsies from the vastus lateralis and blood samples from an antecubital vein were taken at rest and twice during recovery (1 and 4 minutes) from a 60 s one-legged maximal power test on a cycle ergometer. pH one minute after exercise in both the trained and untrained legs following the training period was not different but both were higher than before training. BC increased from 49.9 to 57.8 mumol HCl x g-1 x pH-1 after training (p less than 0.05). Blood lactate levels after exercise were significantly higher for the trained leg when compared to the untrained leg after spring training. Peak and average power output on the 60 s power test increased significantly after training. One-legged aerobic power (VO2max) was significantly increased in the untrained and trained legs. Two-legged VO2max also improved significantly after training. These data suggest that nonbicarbonate buffering capacity and power output can be enhanced with one-legged sprint training. Also, small but significant improvements in VO2max were also observed.

The effects of resistance training on aerobic and anaerobic power of young boys.

A 4-wk interval-type training program incorporating omni-kinetic equipment and stationary cycling elicited an increase in the absolute and relative VO2max of an active group of young boys. The improvement in aerobic function was independent of the training protocols of high velocity-low resistance and low velocity-high resistance. However, the training programs failed to increase anaerobic function as measured by an "all-out" cycle test in which power output was calculated in watts and watts per kilogram for 0- to 15-s and 15- to 30-s work periods. Changes in aerobic and anaerobic functions were independent of physiological maturity as determined by serum testosterone level (ng X dl-1).

The effectiveness of a mini-cycle on velocity-specific strength acquisition.

In order to investigate the rate of strength acquisition from high-velocity resistance (HVR) training, 21 college-aged males were assigned to either HVR training (N = 11) or a control group (N = 10). Subjects trained 4 days weekly over 5 weeks, completing two 20-second sets of all-out exercise separated by 20 seconds of rest at each of three variable hydraulic resistance stations. Initially, subjects completed two circuits, and progressed to three circuits during the third week. Angular velocities of movement were maintained at approximately 3.14 radianslsecond. Increases (p < 0.05) in peak torque during knee extension and flexion, and average peak torque over two 20-second sets of continuous knee extension and flexion exercise at 3.14 radianslsecond were observed after 10 training sessions. After 10 additional training sessions, no further significant increases in performance were observed. These data suggest that velocity-specific strength training .effects may be obtained with relatively small volumes of high-intensity resistance exercise. J Orthop Sports Phys Ther1987;9(4):156-159.