The assessment of ventilatory threshold (Tvent) and maximal oxygen consumption (VO2max) are routine laboratory procedures, yet there are few studies that have directly compared these measurements during different modes of exercise in children. Therefore, the purpose of this study was to compare the physiological and perceptual responses at Tvent and V02max during treadmill and cycle ergometry in prepubertal male children. Ten subjects (M ± SD, 10.2 + 1.3 yrs.) performed a graded exercise test to maximal effort on a treadmill and a cycle ergometer. The order of testing was counterbalanced. The treadmill protocol began at 3.0 mph and 2% grade and progressed in one minute stages. Similarly, the cycle protocol began at 30 watts (W) and progressed 10 W•min-1. For both protocols, each stage was designed to elicit an approximately 3.5 ml-kg-I- min-1 change in V02. In addition, finger stick blood samples were taken at 2, 3, and 5 minutes post exercise in order to assess maximal blood lactate (La) level. Mean V02max on the treadmill (58.2 ± 6.9 ml•kg-l.min-1) was greater (P < 0.05) as compared to the cycle (51.7 ± 7.7ml.kg-'•min-1), with the average difference and the cycle ergometer, V02max is a function of the testing modality. LiKewise, the V02 at Tvent is dependent on the mode of exercise, while Tvent expressed as a percentage of VO2max is independent of mode of exercise. The perceptual responses at Tvent appear to be linked to a percentage of V02max, rather than an absolute V02. / School of Physical Education

No description available.

This thesis investigated the effect of high intensity, intermittent exercise (HIIE) on fat loss in young, sedentary women. It attempted also to identify possible mechanisms underpinning exercise-induced changes in adiposity. Study 1 investigated some of the metabolic and hormonal responses to two variations of HIIE. Sixteen female subjects were tested. The first session involved a cycle ergometer VO2peak test. The next two sessions were completed in random order. After baseline measures the women did 20 min of HIIE. There was a short bout exercise of 8 s work, followed by 12 s relative rest and a long bout exercise of 24 s work followed by 36 s relative rest. Seven subjects had excess postexercise oxygen consumption (EPOC) and resting metabolic rate determined. Both exercise modalities made significant demands on the participants??? oxygen delivery systems. RER diminished over the 20 min of exercise and plasma glycerol concentrations increased. Lactate concentrations rose. Catecholamine concentrations were elevated postexercise. There was an elevated EPOC associated with above baseline fat utilisation. Study 2, a 15-week training study, was a randomised controlled trial comparing the effects of short bout HIIE and steady state (SS) exercise on fat loss. Forty-five women were randomly assigned to one of three groups: HIIE, SS, or control. Preliminary and posttraining testing included a DEXA scan and a VO2peak test including blood collection. All participants completed 3-d diet diaries and maintained their current diet for the course of the study. Participants exercised three times a week for the next 15 weeks under supervision. The HIIE group did 20 min of HIIE (8 s work:12 s rest) at a workload determined from the VO2peak test. The SS group cycled at 60%VO2peak , building to a maximum of 40 min exercise. Both exercise groups increased VO2peak . The HIIE group had a significant loss of total body mass (TBM) and fat mass (FM) when compared to the other groups. There was no change in dietary intake. There have been a number of studies examining the acute effects of HIIE but, to our knowledge, this is the first study examining the chronic effects of this particular exercise protocol.

Exposure to natural altitude using the "live high-train low" method improves athletic endurance performance at sea level by 1-2%. This method can also be employed with hypoxic devices that simulate altitude, but there is limited and conflicting research on their efficacy. Consequently, three studies were undertaken to investigate changes in sea level performance of endurance runners following exposure to altitude simulated with hypoxic tents. The device was chosen because of its potential for incorporation into the athlete's routine. In Study 1, 10 runners received altitude simulated with hypoxic tents (~9 h overnight at 2500-3500 m) and trained at sea level, while 10 runners in the control group performed usual training. Athletes in both groups performed a lactate-threshold test, but only the altitude group performed a run to exhaustion. The effect on 4-mM lactate speed was unclear, owing to poor reliability of this measure. There was a 16% increase in time to exhaustion in the hypoxic conditioning group, equivalent to a 1.9% (90% likely limits, ±1.4%) increase in speed in a time trial. Effects on performance were not apparent four and eight weeks after use of the tents. To improve precision of the effect of the tents and to determine the effects on performance of different durations, a further controlled trial was performed. A reliability study (Study 2) was first conducted to investigate the potential for runs to exhaustion to provide reliable measures of performance. Eight runners performed a test consisting of three runs to exhaustion lasting ~2, ~4 and ~8 min on six occasions over 14 wk. The critical power and log-log models were used to provide factors for converting variability in time to exhaustion into variability in equivalent time-trial time. Variabilities in time to exhaustion expressed as coefficients of variation for predicted 800-3000 m timetrial times were ~1-3%. A crossover study (Study 3) was then conducted in which 11 athletes performed usual (control) training and usual training with altitude exposure by using tents for 25 ± 3 days (mean ± SD) for 8.1 ± 0.6 h.d-1, progressing from a simulated altitude of 2500 m to 3500 m above sea level. Washout period between control and altitude treatments was four weeks. Performance was assessed with treadmill runs to exhaustion as in Study 2. Improvements in mean predicted times (altitude-control) for standard competition distances of 800, 1500 and 3000 m derived from the runs to exhaustion were 1.0% (±1.3%), 1.4% (±1.2%) and 1.9% (±1.5%) respectively. There was some evidence that hypoxic exposure favoured those athletes carrying the I allele for angiotensin converting enzyme. In summary, the main finding from the series of studies is that hypoxic tents are likely to enhance sea level endurance running performance by ~1-2%.

The optimisation of strength and power through resistance training has been the source of debate amongst health professionals and researchers for many years. As resistance training involves the repeated activation and contraction of skeletal muscles, continuous training will ultimately result in a failure to sustain the training intensity especially when performing multiple sets and / or repetitions. Therefore the prescription of rest periods within the training session becomes an important consideration. Relatively short rest periods (60-90 seconds) have been traditionally used for the maximal strength adaptation involving increases in the cross-sectional area of the muscle, whereas longer rest periods (180-300 seconds) have traditionally been used for the maximal strength adaptation involving enhancement of neural function and maximal power adaptation. However, there is very little scientific evidence to support these current practices. In fact, the effect of different rest periods on maximal strength and power development has received very little research attention. Additionally, research that has been conducted in this area has been typified by a number of methodological inconsistencies, within and between studies, which confound scientific understanding. Although traditionally resistance training has employed continuous training schemes with inter-set rest periods, intra-set rest training methods which distribute rest intervals between groups of repetitions have also been investigated. It has been theorised that the short rest periods within the training set allow partial resynthesis of the intramuscular phosphocreatine stores, potentially allowing an athlete to increase their training volume by training at high intensities for longer durations, or performing additional repetitions (Berg, 2003). This is thought to lead to an increased exposure of the muscle to the kinematic and kinetic stimuli thought important for strength and power adaptation whilst minimising performance-inhibiting metabolic accumulation and substrate depletion. However, research into intra-set rest training schemes is still in its infancy, and many of the theories surrounding intra-set rest training are currently unsubstantiated. It is thought that examinations of the acute kinematic, kinetic and blood lactate profiles of continuous and intra-set rest training schemes may enhance scientific understanding regarding the efficacy of intra-set rest training. The purpose of this study was to investigate and compare the acute kinematic, kinetic and blood lactate responses to continuous and intra-set rest loading schemes. Nine male subjects performed an isoinertial Smith machine bench press task (6RM load) with a continuous loading scheme (CONT), an intra-set rest loading scheme equated by total rest time, volume and load (ISRV) and an intra-set rest loading scheme equated by total rest time and load (ISRR). The order of the loading schemes was assigned in a block randomised order with a minimum of 48 hours recovery between each testing session. Attached to the bar of the Smith machine was a linear position transducer that measured vertical displacement with an accuracy of 0.01cm. Displacement data was sampled at 1000Hz and collected by a laptop computer running custom built data acquisition software. Finger prick blood lactate samples were taken from the non-dominant hand using sterile techniques at the following time points: pre-exercise (Pre), immediately post-exercise (P0), five (P5), fifteen (P15) and thirty minutes (P30) post exercise. Blood glucose samples were taken pre-exercise only. It was observed that manipulating the rest period, by increasing the frequency but decreasing the length of each rest period, did not significantly influence the kinematics and kinetics associated with resistance training, but did have an effect on the post-exercise blood lactate response when the load, rest duration and training volume was equated (ISRV). This finding may be of practical significance if fatigue is important in strength development or conversely if power training needs to be performed with minimal fatigue. It was also observed that increasing the frequency of the rest period enabled the subjects to perform a greater number of repetitions (ISRR), resulting in significantly greater kinematics, kinetics and blood lactate accumulation. It may be speculated, therefore, that ISRR training may offer a superior training stimulus for the development of maximal strength and hypertrophy than CONT training methods, as ISRR loading increased the exposure of the muscle to the kinematic, kinetic and metabolic stimuli thought important for the development of these qualities.

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (M.S. Ed.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 51-54). Also available via the Internet.

Thesis (Ph.D.) in Psychology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 152-176).

Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 99-111).

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "May 1998." Typescript. Vita. Includes bibliographical references (leaves 103-112). Also available on the Internet.