Effects of a 6-month exercise program pilot study on walking economy, peak physiological characteristics, and walking performance in patients with peripheral arterial disease.

The purpose of this study was to examine the effects of a 6-month exercise program on submaximal walking economy in individuals with peripheral arterial disease and intermittent claudication (PAD-IC). Participants (n = 16) were randomly allocated to either a control PAD-IC group (CPAD-IC, n = 6) which received standard medical therapy, or a treatment PAD-IC group (TPAD-IC; n = 10) which took part in a supervised exercise program. During a graded treadmill test, physiological responses, including oxygen consumption, were assessed to calculate walking economy during submaximal and maximal walking performance. Differences between groups at baseline and post-intervention were analyzed via Kruskal-Wallis tests. At baseline, CPAD-IC and TPAD-IC groups demonstrated similar walking performance and physiological responses. Postintervention, TPAD-IC patients demonstrated significantly lower oxygen consumption during the graded exercise test, and greater maximal walking performance compared to CPAD-IC. These preliminary results indicate that 6 months of regular exercise improves both submaximal walking economy and maximal walking performance, without significant changes in maximal walking economy. Enhanced walking economy may contribute to physiological efficiency, which in turn may improve walking performance as demonstrated by PAD-IC patients following regular exercise programs.

Identification and reliability of pacing strategies in outrigger canoeing ergometry.

This study examined the pacing strategies utilised; and the performance reproducibility during repeated outrigger canoeing ergometer time trials. Trained female outrigger canoeists (N=11) completed four 1000m outrigger canoe ergometer time trials. There was a significant 1.5% improvement in 1000m time in trial four compared to trial one. A fast start strategy was adopted in 36 of the 44 trials (82%) followed by a deceleration during the mid stages. As trials progressed there was an increased adoption of negative pacing (fast finish) between the last two splits, indicating a learning effect of pacing strategy across repeated trials. These results demonstrate that although some performance improvement was evident between the first and fourth time trials, the 1000m outrigger ergometer time trial is a reliable test that may be used as a tool to assist with crew selection and performance monitoring. Further, on account of the variation in pacing strategy noted in the fourth trial, the authors recommend utilising one familiarisation session and one test session when assessing performance such that learning or training adaptations resulting from multiple trials do not impact on results.

The influence of a long term exercise program on lower limb movement variability and walking performance in patients with peripheral arterial disease.

The purpose of this study was to examine the effects of a 12month exercise program on lower limb movement variability in patients with peripheral arterial disease (PAD). Participants (n=21) with an appropriate history of PAD and intermittent claudication (IC) volunteered for this study and were randomly allocated to either a control group (CPAD-IC) (n=11), which received normal medical therapy and a treatment group (TPAD-IC) (n=10), which received normal medical therapy treatment and a 12month supervised exercise program. All participants underwent 2D joint angular kinematic analysis during normal walking to assess lower limb movement variability and walking speed. Between-group differences were analyzed via mixed measures ANOVA. The 12month supervised exercise program made no significant impact on the lower limb movement variability or walking speed of the TPAD-IC group as determined by either intralimb joint coordination or single joint analysis techniques. Long term supervised exercise programs do not appear to influence the lower limb movement variability of PAD-IC patients.

Blood lactate, heart rate and rating of perceived exertion responses of elite surf lifesavers to high-performance competition.

A paucity of empirical research exists into surf lifesaving competition from which coaches and athletes may formulate training and recovery strategies. Seventeen (male=9; female=8) high-performance surf lifesavers (21.2+/-3.9 years) contested multiple rounds of team and individual events at a 2-day surf lifesaving competition. Individual events consisted of the multi-discipline ironman (IRON), paddle board (BOARD) and surf swim (SWIM). Blood lactate (BLa), rating of perceived exertion (RPE) and heart rate (HR) were determined following heats, semi-finals and final. IRON HR and RPE following semi-finals (153.0+/-21.6beatsmin(-1) and 14.4+/-1.5) and final (171.0+/-9.1beatsmin(-1) and 19.1+/-0.2) were greater than heats (141.8+/-17.2beatsmin(-1) and 12.0+/-1.9; p<0.05) and final BLa (10.5+/-2.8mmolL(-1)) was greater than heats (5.8+/-3.6mmolL(-1); p<0.05). BOARD BLa and HR were greater after the final (9.0+/-2.8mmolL(-1) and 159.0+/-19.9beatsmin(-1)) compared to heats (4.7+/-2.4mmolL(-1) and 133.0+/-17.1beatsmin(-1); p<0.05). No significant differences were identified for SWIM. RPE-HR relationships were identified for pooled IRON and BOARD results following semi-finals (0.668; p<0.05) and finals (r=0.741; p<0.05). In conclusion, high-performance surf lifesavers employ race strategies with all-out maximal exercise limited to semi-finals and finals.

Lower limb movement variability in patients with peripheral arterial disease.

BACKGROUND: Peripheral arterial disease is a chronic obstructive disease of the arteries of the lower limb caused by atherosclerosis. The resultant decrease in blood flow can result in symptoms of pain in the lower limb on exercise known as intermittent claudication. Exercise induced pain is experienced in the calves, thigh or buttocks restricting activities of daily living and thus reducing quality of life. METHODS: This study investigated lower limb movement variability in individuals with peripheral arterial disease-intermittent claudication (n=28) compared to individuals without peripheral arterial disease-intermittent claudication (control, n=25). A further aim was to examine the efficacy of various techniques used to describe single joint movement variability. All participants underwent two-dimensional angular kinematics analysis of the lower limb during normal walking. Single joint movement variability was measured using linear (spanning set and coefficient of variation) techniques. Between group differences were examined by one-way ANOVA. FINDINGS: The peripheral arterial disease-intermittent claudication participants displayed significantly higher levels of lower limb movement variability in all joints when assessed using the coefficient of variation technique. There were no significant between group differences using the spanning set technique. INTERPRETATION: Individuals with peripheral arterial disease-intermittent claudication have higher levels of lower limb movement variability and reduced walking speed compared to healthy age and mass matched controls. This variability may be an adaptation to the gradual onset of ischaemic pain in this population.

Effects of a 12-month exercise program on cardiorespiratory health indicators of Vietnam War veterans resident in the tropics.

OBJECTIVE: To measure the effect of a combined aerobic and resistance exercise program on key cardiovascular disease risk factors (i.e. body composition or anthropometry and cardiorespiratory function) of Australian male, Vietnam War veterans living in the tropics. DESIGN: Twelve-month exercise program with assessments at commencement, 3, 6 and 12 months. SETTING: North Queensland regional centre. PARTICIPANTS: Australian male, Vietnam War veterans (n = 164) resident in north Queensland. MAIN OUTCOME MEASURES: Measurement of heart rate, blood pressure, skinfold and girth measurements, exercise heart rate response and estimated aerobic capacity to determine whether the implementation of a simple aerobic and resistance exercise program could positively change selected cardiovascular disease risk factors in Vietnam Veterans. RESULTS: Significant improvements were reported for systolic blood pressure (131.1 (SD 15.7) reduced to 122.7 (12.4) mmHg), diastolic blood pressure (82.7 (9.1) reduced to 76.3 (10.3) mmHg), resting heart rate (73 (11) reduced to 69 (11) bpm), sum of skinfolds (127.5 (40.3) reduced to 99.5 (32.1) mm), waist girth (103.2 (12.0) reduced to 100.5 (12.1) cm), hip girth (105.3 (9.6) reduced to 103.7 (10.4) cm) and aerobic capacity (2.17 (0.39) increased to 2.36 (0.34) L min(-1)). CONCLUSION: Participation in a combined aerobic and resistance training program elicited significant anthropometric and cardiorespiratory benefits that might lead to a decreased risk of developing cardiovascular disease for male Vietnam War veterans resident in rural and regional areas.

Effects of a long-term exercise program on lower limb mobility, physiological responses, walking performance, and physical activity levels in patients with peripheral arterial disease.

OBJECTIVE: The purpose of the study was to examine the effects of a 12-month exercise program on lower limb mobility (temporal-spatial gait parameters and gait kinematics), walking performance, peak physiological responses, and physical activity levels in individuals with symptoms of intermittent claudication due to peripheral arterial disease (PAD-IC). METHODS: Participants (n = 21) with an appropriate history of PAD-IC, ankle-brachial pressure index (ABI) <0.9 in at least one leg and a positive Edinburgh claudication questionnaire response were prospectively recruited. Participants were randomly allocated to either a control PAD-IC group (CPAD-IC) (n = 11) that received standard medical therapy and a treatment PAD-IC group (TPAD-IC) (n = 10), which also took part in a 12-month supervised exercise program. A further group of participants (n = 11) free of PAD (ABI >0.9) and who were non-regular exercisers were recruited from the community to act as age and mass matched controls (CON). Lower limb mobility was determined via two-dimensional video motion analysis. A graded treadmill test was used to assess walking performance and peak physiological responses to exercise. Physical activity levels were measured via a 7-day pedometer recording. Differences between groups were analyzed via repeated measures analysis of variance (ANOVA). RESULTS: The 12-month supervised exercise program had no significant effect on lower limb mobility, peak physiological responses, or physical activity levels in TPAD-IC compared with CPAD-IC participants. However, the TPAD-IC participants demonstrated significantly greater walking performance (171% improvement in pain free walking time and 120% improvement in maximal walking time compared with baseline). CONCLUSION: The results of this study confirm that a 12-month supervised exercise program will result in improved walking performance, but does not have an impact on lower limb mobility, peak physiological responses, or physical activity levels of PAD-IC patients.

Effect of exercise mode on heart rate variability during steady state exercise.

This study examined the effect of exercise mode on geometrical, and time and frequency domain measures of heart rate variability (HRV) during steady-state, moderate intensity exercise of the same HR. Seventeen healthy, active male participants volunteered for this study and completed a treadmill VO2max determination. One week later, cardiorespiratory, perceptual and HRV measures were recorded during seated rest (15 min) and consecutive bouts (15 min) of steady-state exercise at 50 and 65% of maximal HR. Exercise was performed using either upper body (arm ergometer), lower body (cycle) or whole body (treadmill) modes. Separated by 1 week and in a random order, participants undertook the same procedures with the remaining exercise modes. Cardiorespiratory, perceptual and HRV responses were determined during rest and steady-state exercise and analysed by two-way (mode vs. stage) repeated measures ANOVA and post hoc pairwise comparisons. Apart from a reduced respiratory rate during lower body exercise, whole and lower body exercise resulted in similar cardiorespiratory, perceptual and HRV responses. Compared to whole or lower body exercise, upper body exercise resulted in significantly (P < 0.05) greater measures of HRV particularly those within the very low (0-0.04 Hz) and low (0.04-0.15 Hz) frequency bands, greater rating of perceived exertion and less oxygen consumption. Upper body, moderate intensity exercise resulted in greater HRV compared to whole or lower body exercise with further studies necessary to elucidate the mechanisms and clinical implications for this greater HRV.

Thermoregulatory responses of junior lifesavers wearing protective clothing.

This study investigated the influence of protective clothing worn to prevent marine stinger envenomation on the thermoregulatory responses of pre-pubescent surf lifesavers exercising in situ under hot and humid conditions (27 degrees C, 78% relative humidity). Participants performed beach and water activities typically associated with junior surf lifesaving competition in a randomised cross-over design on two separate occasions 7 days apart: one wearing a full-length Lycra stinger suit (S) and one wearing normal swimwear (SW). Skin (T(SK)) and core (T(C)) body temperatures, skin blood flow (SKBF), heart rate (HR), body mass, thermal comfort and perceived effort were assessed pre-, mid- (following beach activities) and post-exercise (following water activities). Sweat rates were compared between S and SW. T(C) was greater following beach activities for S (37.78 degrees C+/-0.06) compared to SW (37.60 degrees C+/-0.07; p<0.05) and male participants experienced greater T(C) (37.97 degrees C+/-0.09) than their female counterparts (37.71 degrees C+/-0.07 degrees C). T(SK) following both the beach and water activities were lower than pre-exercise (p<0.05). SKBF was significantly increased for calf across time (p<0.01). Male participants experienced a higher HR for S compared to female participants (p<0.01) while the opposite applied to SW (p<0.01). There were no gender or between-condition differences for sweat rate or perceived effort. There was evidence of heat storage while stinger suits were worn during beach activities in the absence of any differences in exercise intensity or sweat rate. The results of the present study suggest that the stinger suits should be limited to water-based activities.

Intralimb coordination variability in peripheral arterial disease.

BACKGROUND: Increased variability has been traditionally associated with decreased movement performance due to disease and aging. However, recent research indicates that variability may be of functional importance in motor control. Thus the purpose of this study was to determine whether individuals with peripheral arterial disease and suffering from intermittent claudication have reduced intralimb joint coordination variability compared to individuals without peripheral arterial disease. A further aim was to examine the efficacy of various techniques used to describe intralimb joint coordination variability. METHODS: Participants with peripheral arterial disease and suffering from intermittent claudication (n=28) were selected based on an appropriate history of peripheral arterial disease and intermittent claudication, ankle brachial pressure index <0.9 in at least 1 leg and a positive Edinburgh claudication questionnaire response. A further group of participants (n=25) free of peripheral arterial disease (ankle brachial pressure index >0.9) and who were non-regular exercisers were recruited from the community to act as age and mass matched controls. All participants underwent 2D angular kinematics analysis during normal walking. Intralimb coordination variability was measured using parameterization, vector coding and normalized root mean square techniques applied to relative motion plots of various joint couplings. Differences between groups were examined by one-way ANOVA. FINDINGS: Participants with peripheral arterial disease and suffering from intermittent claudication displayed significantly greater intralimb joint coordination variability than age and mass matched controls participants for all joint couplings using all intralimb joint coordination variability techniques. INTERPRETATION: These findings suggest that higher levels of intralimb joint coordination variability of the lower limbs in participants with peripheral arterial disease and suffering from intermittent claudication may be an adaptation of the motor control system to deal with perturbations associated with the gradual onset of claudication pain.

Exercise self-efficacy of postmenopausal women resident in the tropics.

OBJECTIVES: Weight gain and the associated increased risk of coronary artery disease are associated with the postmenopausal period. However, moderate intensity physical activity may be cardioprotective in this period. Australian women remain predominately sedentary despite the health benefits of regular exercise. Self-efficacy is an important predictor of exercise behaviour influencing exercise adoption when faced with potential barriers. Determination of exercise self-efficacy levels and the most significant barriers to exercise is necessary for the success of intervention programs for this population. METHODS: Postmenopausal women (N=101) resident in tropical North Queensland were recruited via announcements in local media, service club newsletters and electronic bulletin boards. Following data collection, participants were categorised as exercisers (n=53) or non-exercisers (n=48) based on whether they had performed a minimum of 150 min of accumulated moderate intensity exercise in the past 7 days. Exercise self-efficacy was determined via questionnaire. RESULTS: Results indicated that exercisers had a higher level of exercise self-efficacy and felt significantly more confident to exercise when faced with barriers compared to non-exercisers (p<.001). Discriminant function analysis found that exercise self-efficacy provided the greatest discrimination between exercisers and non-exercisers. The barrier items of conflicting schedules, difficulty getting to an exercise location and the weather were the main contributors to discrimination between exercisers and non-exercisers. CONCLUSIONS: Findings suggest that future intervention programs should aim to increase exercise self-efficacy and address these barriers so that more postmenopausal women resident in North Queensland can obtain the health benefits of exercise.

Relationship between temporal-spatial gait parameters, gait kinematics, walking performance, exercise capacity, and physical activity level in peripheral arterial disease.

OBJECTIVE: Impaired physical function is a feature of patients with peripheral arterial disease (PAD) who present with symptoms of intermittent claudication (PAD-IC). Previous research found that temporal-spatial gait parameters do not discriminate between PAD-IC patients and control subjects during normal and maximal walking even though PAD-IC patients have decreased physical function characteristic of the disease. This study examined the hypothesis that patients with PAD-IC would demonstrate decreased temporal-spatial gait parameters, gait kinematics, walking performance, physiologic responses to exercise, and physical activity level compared with control subjects. The aim was to examine the temporal-spatial gait parameters and gait kinematics of individuals with PAD-IC and to determine the relationship between these variables and walking performance, exercise capacity, and physical activity level in these individuals. METHOD: A cross-sectional study of 28 PAD-IC subjects (IC) and 25 controls (CON) matched for age and mass was conducted in a medical faculty human performance laboratory. IC subjects had a history of PAD, ankle-brachial pressure index (ABI)<0.9 in at least one leg, and a positive Edinburgh Claudication Questionnaire response. Gait characteristics were determined by two-dimensional motion analysis. A graded treadmill test was used to assess walking performance and peak physiologic responses to exercise. Physical activity levels were measured by analysis of 7-day pedometer recording motion. Differences between groups were examined by one-way analysis of covariance. RESULTS: Compared with CON, IC temporal-spatial gait parameters were significantly lower (P<.05), except for single support ipsilateral limb time. IC subjects spent a greater percentage of time in gait support phases, took longer to complete a stride, and had reduced stride length and walking speeds during the gait cycle. IC joint angular kinematics showed significantly reduced displacement of ankle plantar flexion (P=.017), knee range of motion (P=.021), and hip extension (P=.016) compared with the CON subjects during the gait cycle. All joint minimum and maximum angular velocities and accelerations, walking physiologic responses, and physical activity levels were significantly lower for IC compared with the CON subjects. CONCLUSION: IC subjects walk with a shuffling gait pattern indicated by reduced joint angular displacement, velocities, and accelerations that results in reduced walking performance and physiologic responses and physical activity compared with controls matched for age, mass, and physical activity.

Kinematic responses to plyometric exercises conducted on compliant and noncompliant surfaces.

Jumping is an important performance component of many sporting activities. A number of training modalities have been used to enhance jumping performance including plyometrics. The positive effects of plyometric training on jumping performance are a function of the stretch-shortening cycle phenomenon. However, there has been little research on the effects of the surface on jumping performance. This study examined the effects of performing 2 different plyometric exercises, depth jump (DJ) and counter movement jump (CMJ), on noncompliant (ground) and compliant (mini-trampoline) surfaces. Male participants (N = 20; age = 21.8 +/- 3.8 years; height = 184.6 +/- 7.6 cm; mass = 83.6 +/- 8.2 kg) randomly performed 10 CMJ and 10 DJ on compliant and noncompliant surfaces. Kinematic data were determined via 2-dimensional high-speed video. There were significant (p < 0.05) differences in DJ and CMJ joint and segment range of movement for ankle, knee, hip and trunk, indicating less crouch when the participants performed plyometric exercises on the compliant surface.

Effect of shoulder angle on physiological responses during incremental peak arm crank ergometry.

This study examined the effect of shoulder angle and gender on physiological and perceptual responses during incremental peak arm ergometry. Healthy adults (nine males, seven females) volunteered for the study and completed an incremental arm ergometry test on two separate occasions at two different shoulder angles (90 degrees and 45 degrees). Initial work rate was set at 16 W x min-1 and was increased progressively until exhaustion. Cardiorespiratory and perceptual responses were recorded at the end of each minute and compared using separate three-way (position x work rate x gender) repeated-measures analyses of variance. The systematic bias of peak responses was examined using separate two-way (position x gender) analyses of variance, while reproducibility of these parameters was explored using intraclass correlation coefficients, measurement bias/ratio, and 95% ratio limits of agreement. Despite a significantly greater peak heart rate for the 45 degrees position, cardiorespiratory and perceptual responses were similar at peak exercise for both positions. Peak values for all variables, although similar, demonstrated similar and large inter-test variability for men and women. Reduction of the shoulder joint angle to 45 degrees did not enhance peak work rate and peak oxygen consumption during seated upper body exercise. Due to the large inter-test variability, arm ergometry should be conducted using the same seated position.

The effects of resisted sprint training on acceleration performance and kinematics in soccer, rugby union, and Australian football players.

Acceleration is a significant feature of game-deciding situations in the various codes of football. However little is known about the acceleration characteristics of football players, the effects of acceleration training, or the effectiveness of different training modalities. This study examined the effects of resisted sprint (RS) training (weighted sled towing) on acceleration performance (0-15 m), leg power (countermovement jump [CMJ], 5-bound test [5BT], and 50-cm drop jump [50DJ]), gait (foot contact time, stride length, stride frequency, step length, and flight time), and joint (shoulder, elbow, hip, and knee) kinematics in men (N = 30) currently playing soccer, rugby union, or Australian football. Gait and kinematic measurements were derived from the first and second strides of an acceleration effort. Participants were randomly assigned to 1 of 3 treatment conditions: (a) 8-week sprint training of two 1-h sessions x wk(-1) plus RS training (RS group, n = 10), (b) 8-week nonresisted sprint training program of two 1-h sessions x wk(-1) (NRS group, n = 10), or (c) control (n = 10). The results indicated that an 8-week RS training program (a) significantly improves acceleration and leg power (CMJ and 5BT) performance but is no more effective than an 8-week NRS training program, (b) significantly improves reactive strength (50DJ), and (c) has minimal impact on gait and upper- and lower-body kinematics during acceleration performance compared to an 8-week NRS training program. These findings suggest that RS training will not adversely affect acceleration kinematics and gait. Although apparently no more effective than NRS training, this training modality provides an overload stimulus to acceleration mechanics and recruitment of the hip and knee extensors, resulting in greater application of horizontal power.

Association of obesity and metabolic syndrome with the severity and outcome of intermittent claudication.

BACKGROUND: Obesity is recognized as an independent predictor of coronary artery disease; however, its importance in peripheral arterial disease is less clear. The aim of this study was to assess the association between obesity and the severity and outcome of intermittent claudication. METHODS: This study was a prospective cohort study based at a tertiary referral center. Sixty patients with intermittent claudication selected for conservative treatment were assessed for obesity and metabolic syndrome by using the International Diabetes Federation definition. Other risk factors, including diabetes, hypertension, smoking history, serum lipids, adipocytokines, and C-reactive protein, were measured by clinical and blood assessment. Obesity and metabolic syndrome were related to the severity of peripheral arterial disease, defined by ankle-brachial pressure index and graded treadmill measured maximum walking distance (MWD) and initial claudication distance, by using multiple linear regression analysis allowing for traditional atherosclerotic risk factors. Patients were followed up for 24 months, and combined outcome was reported in terms of death, cardiovascular events, or requirement for revascularization. The effect of obesity and metabolic syndrome on outcome was investigated by using Kaplan-Meier and Cox proportional hazard analysis. RESULTS: Obesity and serum adiponectin were independently associated with the severity of peripheral arterial disease measured by ankle-brachial pressure index (P = .03 and .001), initial claudication distance (P = .009 and .03), and MWD (P = .001 and .04). Metabolic syndrome was independently associated only with MWD (P = .02). By 24 months, outcome events occurred in 37% +/- 7% and 43% +/- 9% of patients with metabolic syndrome or obesity, respectively, compared with 0% and 11% +/- 6% of those without these diagnoses. Waist circumference independently predicted the likelihood of outcome events (relative risk, 1.16; 95% confidence interval, 1.08-1.26; P < .001). CONCLUSIONS: These findings, if confirmed in other cohorts, suggest the importance of treating obesity in patients with intermittent claudication. Serum adiponectin concentrations may be an important guide to the efficacy of treatment in patients with intermittent claudication and obesity.

Pre-pubertal children and exercise in hot and humid environments: a brief review.

The ability of pre-pubertal children to regulate their body temperature under thermoneutral environments is similar to that of an adult albeit via differing routes. However, this ability is challenged when exposed to extreme environments. Thermoregulatory responses of pre-pubertal children differ from adults via adaptations that occur during growth and maturation and disadvantage children when exercising in hot and humid environments. When ambient temperatures exceed that of the skin, an influx of thermal energy from the environment increases thermal stress. When coupled with exercise, the increased thermal stress results in reduced physical performance and an increased risk of developing heat-related illness. Evidence suggesting the severity of heat-related illness is greater in pre-pubertal children than adults is inconclusive because age-related differences in thermoregulatory responses are attributed to either morphologic or functional changes. Additionally, the majority of research on pre-pubertal children exercising in the heat has been maturational or comparative studies with adults conducted in the near absence of convective cooling, complicating extrapolation to field-based environments. However, current consensus is that pre-pubertal children are disadvantaged when exercising in extreme temperatures and that care should be taken in preparing for and conducting sporting activities in hot and humid environments for pre-pubertal children. Key pointsPre-pubertal children's ability to thermoregulate when exposed to hot and humid environments is deficient compared to adults.Research into the severity of heat-related illness in pre-pubertal children is inconclusive.Discretion should be used in applying findings from indoor studies to outdoor activities due to the influence of the velocity of circulating air on thermoregulation.

Physiological and cognitive responses to caffeine during repeated, high-intensity exercise.

This study investigated the effects of caffeine on repeated, anaerobic exercise using a double-blind, randomized, crossover design. Seventeen subjects (five female) underwent cognitive (reaction time, number recall) and blood (glucose, potassium, catecholamines, lactate) testing before and after consuming caffeine (6 mg/kg), placebo, or nothing (control). An exercise test (two 60 s maximal cycling bouts) was conducted 90 min after caffeine/placebo consumption. Plasma caffeine concentrations significantly increased after caffeine ingestion, however, there were no positive effects on cognitive or blood parameters except a significant decrease in plasma potassium concentrations at rest. Potentially negative effects of caffeine included significantly higher blood lactate compared to control and significantly slower time to peak power in exercise bout 2 compared to control and placebo. Caffeine had no significant effect on peak power, work output, RPE, or peak heart rate. In conclusion, caffeine had no ergogenic effect on repeated, maximal cycling bouts and may be detrimental to anaerobic performance.

Creatine supplementation and its effect on musculotendinous stiffness and performance.

Anecdotal reports suggesting that creatine (Cr) supplementation may cause side effects, such as an increased incidence of muscle strains or tears, require scientific examination. In this study, it was hypothesized that the rapid fluid retention and "dry matter growth" evident after Cr supplementation may cause an increase in musculotendinous stiffness. Intuitively, an increase in musculotendinous stiffness would increase the chance of injury during exercise. Twenty men were randomly allocated to a control or an experimental group and were examined for musculotendinous stiffness of the triceps surae and for numerous performance indices before and after Cr ingestion. The Cr group achieved a significant increase in body mass (79.7 +/- 10.8 kg vs. 80.9 +/- 10.7 kg), counter movement jump height (40.2 +/- 4.8 cm vs. 42.7 +/- 5.9 cm), and 20-cm drop jump height (32.3 +/- 3.3 cm vs. 35.1 +/- 4.8 cm) after supplementation. No increase was found for musculotendinous stiffness at any assessment load. There were no significant changes in any variables within the control group. These findings have both performance- and injury-related implications. Primarily, anecdotal evidence suggesting that Cr supplementation causes muscular strain injuries is not supported by this study. In addition, the increase in jump performance is indicative of performance enhancement in activities requiring maximal power output.