Steve R. Bird

Peak power predicts performance power during an outdoor 16.1-km cycling time trial

PURPOSE To assess i) the reproducibility of peak power output recorded during a maximal aerobic power test (MAP), and ii) its validity to predict endurance performance during a field based 16.1-km time trial (16.1-km TT). METHODS Two studies were completed: for part I, nine subjects performed three MAP tests; for part II, 16 subjects completed a MAP test and 16.1-km TT. Power output was recorded using an SRM power meter and was calculated as peak power output (PPO) recorded during 60 s of MAP and mean power output for the 16.1-km TT (16.1-km TT(PO)). RESULTS There was no difference between PPO recorded during the three MAP trials, mean coefficient of variation for individual cyclists was 1.32% (95%CI = 0.97-2.03), and test-retest reliability expressed as an intraclass correlation coefficient was 0.99 (95%CI = 0.96-1.00). A highly significant relationship was found between PPO and 16.1-km TT(PO) (r = 0.99, P < 0.001) but not for PPO and 16.1-km TT time (r = 0.46. P > 0.05). CONCLUSION The results show that PPO affords a valid and reliable measure of endurance performance which can be used to predict average power during a 16.1-km TT but not performance time.

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men.

OBJECTIVE:To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.DESIGN:Cross-sectional study of 113 nonsmoking men aged 30–45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (≥100 cm) subgroups.MEASUREMENTS:Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.RESULTS:Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.CONCLUSIONS:These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

The Physiology of the Highly Trained Female Endurance Runner

Continuing improvements in the performance of female endurance runners and increasing levels of participation have generated the need to know more about the physiology of this group. Specific research is needed in this area, as data referring to male endurance runners cannot legitimately be applied to the female endurance runner because of their markedly different physiological and hormonal profiles. Recent developments in our understanding of an athlete’s physiology (mainly in relation to the male endurance runner) have revealed new areas of interest that need to be assessed with specific reference to the female athlete.Relatively little attention has been directed towards identifying the major physiological characteristics of the highly trained/elite female endurance runner in general, and that which has been published on such factors and the effects of the menstrual cycle have produced equivocal results. Moreover, the impact of such training upon the menstrual cycle and endurance running performance is a controversial area, especially when assessing its subsequent impact on health-related issues. Reports of the condition referred to as the ‘female athlete triad’ have increased in recent years, with a decrease in bone mineral density predisposing the female athlete to increased risks of stress fractures. The aetiology of this triad is multifactorial, with such risk factors including nutrition, menstrual status, training intensity and frequency, body size and composition and psychology/physical stress. However, research limitations and flaws have lead to controversy in the literature regarding the immediate and long term effects of the triad on the female athlete. Likewise, the effects of the oral contraceptive pill on health and endurance performance also remain elusive, with a dearth of research pertaining to how oral contraceptive agents can aid athletic performance and the long term health of the female athlete.The purpose of this paper is to critically appraise the existing literature to provide a current review of the physiological scientific knowledge base in relation to the female athlete, health, training and performance, with suggestions for future areas of research. It is well known that certain menstrual and health-related performance factors of the female athlete, that is, physiological predictors of performance and body fat, have been extensively investigated over the last 30 years. However, a variety of methodological flaws and inconsistencies are present within the research and thus only the most prominent and well controlled studies within this area over the past 30 years will be referred to.

Assessment of blood lactate: practical evaluation of the Biosen 5030 lactate analyzer

PURPOSE The aim of this study was to assess the validity and reliability of the Biosen 5030 lactate analyzer compared with a YSI 2300 lactate analyzer and a Kodak Ektachem DTII in a practical laboratory study context. METHODS To assess validity, 144 triplicate capillarized blood samples, across a range of values, were analyzed using the three analyzers. To assess reliability a further 665 samples were repeat analyzed. Temporal stability was determined by the reanalysis of resting and maximal exercise blood samples, after a period of storage ranging from 7 to 20 h, at room temperature. To measure inter- and intra-investigator reliability, 20 resting samples were taken from three different subjects by different investigators and a coefficient of variation was determined. RESULTS There were strong relationships between the Biosen, the YSI (r2 = 0.97), and the Kodak Ektachem (r2 = 0.91). An analysis of Biosen compared with YSI revealed a positive bias of 0.37 mmol x L(-1) (95% limits of agreement, -0.85 to 1.59 mmol x L(-1)). The test-retest reliability correlation was significant (r2 = 0.99, P < 0.05), but a paired t-test revealed a small (0.03 mmol x L(-1), P < 0.05) significant difference. The coefficient of variation from the three investigators across the 20 samples ranged from 1.3 to 3%. Blood lactate concentration in resting blood samples did significantly increase in value (0.2 mmol x L(-1), P < 0.05) after 7-h exposure to the air, whereas there was no change in maximal exercise blood lactate values after 20-h exposure to the air. CONCLUSIONS In a practical context, the Biosen 5030 lactate analyzer was comparable to the other analyzers giving fast reliable measures of blood lactate concentrations over the full range of values, which remained stable over extended periods at room temperature.

Correlates of simulated hill climb cycling performance

The aim of this study was to assess the relationship between several commonly used aerobic and anaerobic cycle ergometer tests and performance during a treadmill cycling hill climb. Eight competitive cyclists (age 27 +/- 7 years; body mass 73.2 +/- 5.2 kg; height 177 +/- 6 cm; mean +/- s) completed six tests in random order: a lactate minimum test; a Wingate anaerobic power test; and two 6-km climbs at 6% and two 1-km climbs at 12% gradient performed on a motorized treadmill. The mean times and power outputs for the 6-km and 1-km climbs were 16:30 +/- 1:08 min:s and 330 +/- 17.8 W, and 4:19 +/- 0:27 min:s and 411 +/- 24.4 W, respectively. The best individual predictor of 6-km and 1-km performance times was the time for the corresponding climb at the other distance (r = 0.97). The next strongest predictor of both hill climb performances was the average power produced during the Wingate test divided by body mass. Stepwise regression analysis showed that the two variables contributing most to the prediction equation for both climbs were the Wingate average power per unit of body mass and maximal aerobic power divided by total mass (rider + bike), which together accounted for 92 and 96% of the variability in the 6-km and 1-km climbs. In conclusion, among competitive cyclists, the Wingate average power per unit of body mass was the best single predictor of simulated cycling hill climb performance at the distance and gradient used.

Reliability of an air-braked ergometer to record peak power during a maximal cycling test

PURPOSE To assess the reliability of the Kingcycle ergometer, this study compared peak power recorded using a Kingcycle and SRMTM power meters during Kingcycle maximal aerobic power tests. METHODS The study was completed in two parts: for part 1, nine subjects completed three maximal tests with a stabilizing kit attached to the Kingcycle rig and calibration of the Kingcycle checked against SRM (MAP(C)); and for part 2, nine subjects completed two maximal tests without the stabilizing kit and the Kingcycle calibrated using the standard procedure (MAP(S)). Each MAP(C) test was separated by 1 wk; however, MAPs tests were separated by 54 +/- 32 d, (mean +/- SD). Testing procedure was repeated for each MAP and peak power output was calculated as the highest average power output recorded during any 60-s period of the MAP test using the Kingcycle (King(PPO)) and SRM (SRM(PPO)). RESULTS Coefficient of variations (CVs) for King(PPO) were larger than those of SRM(PPO); 2.0% (95%CI = 1.5-3.0) versus 1.3% (95%CI = 1.0-2.0) and 4.6% (95%CI = 2.7-7.6) versus 3.6% (95%CI = 2.1-6.0) for MAPC( and MAP(S), respectively. During all tests, King(PPO) was higher than SRM(PPO) by an average of approximately 10% (P < 0.001). CONCLUSIONS Investigators should be aware of the discrepancy between the two systems when assessing peak power and that SRM cranks provide a more reproducible measure of peak power than the Kingcycle ergometer.

Differences between the sexes and age-related changes in orienteering speed

The aim of this study was to assess the effects of the age and sex of the competitor on orienteering speed during competitive events. The results of the fastest three male and fastest three female competitors in each 5-year age band (21-79 years), from four national orienteering events, were analysed. The data for age and orienteering speed were log-transformed and regression analyses were conducted to determine the relationships between age and sex and orienteering speed. For comparison, data for the fastest Great Britain finisher in the 10,000-m track and 10-km cross-country events for age groups 40-69 years at the World Masters Championships were also analysed. The results showed that, before the age of 40 years, there was no substantial slowing in orienteering speed for males (0.5-4.2% per decade) but a moderate decline (4.7-10.0% per decade) for females. After the age of 45 years, the orienteering speed of males and females slowed by 13 - 2% and 16 - 4% per decade (mean - s ), respectively, until around the age of 69, after which the deterioration was accentuated. The orienteering speed of the females was 81 - 4, 74 - 6 and 69 - 7% that of the males at ages 21, 45 and 65 years, respectively. The magnitudes of the age-related slowing of orienteering speed and of the difference in orienteering speed between males and females aged 45 years and over were greater than those reported for the other endurance running events. This may reflect the physical demands of running in orienteering terrain, tactical and cognitive aspects of the sport, or sociocultural aspects of the participating population.

The use of doppler and atrioventricular plane motion echocardiography for the detection of changes in left ventricular function after training

Abstract In this study we compared the efficacy of Doppler and atrioventricular plane motion echocardiography in detecting the changes in left ventricular function caused by moderate-intensity training. Fifty-nine healthy men and women (aged 40–68 years) were divided into either a group of walkers (n = 32) or controls (n = 27). Pre-intervention, there were no significant differences between the groups for gender, age, height, mass or predicted maximal oxygen consumption. The walkers completed a progressive 18-week walking programme that resulted in an estimated mean gross energy expenditure whilst walking of 4.0 (1.3) MJ · week−1 for the duration of the study, and 5.9 (1.7) MJ · week−1 during the final 6 weeks. After the 18-week programme there were no significant changes in Doppler measures of early or late filling velocities. However, the walkers showed an increase in the velocity of relaxation (1.2 cm · s−1) (P < 0.02) of the left free wall, as measured using atrioventricular plane motion echocardiography, while the controls showed no significant changes. The findings suggest that atrioventricular plane motion echocardiography is more sensitive than Doppler echocardiography in detecting the left ventricular changes caused by exercise intervention.

Factor XIIa and triacylglycerol rich lipoproteins: responses to exercise intervention

Objectives—(a) To determine if factor XIIa (FXIIa) would be sensitive to change from exercise intervention in a group of previously sedentary/low active middle aged men and women; (b) to investigate further the previously reported relation between FXIIa and triacylglycerol (TAG) rich lipoproteins. Methods—Thirty seven men (mean (SD) age 57 (7) years) and 60 women (mean age 54 (7) years) completed the study. Before the intervention, these subjects were randomly allocated to a group of walkers (n = 81) or controls (n = 16). Before and after an 18 week walking intervention, fasted blood samples were collected and analysed for FXIIa, TAG, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and apolipoprotein (apo) B. Results—Kruskal-Wallis analysis of data obtained before the intervention showed no significant differences (p>0.4) between the walking and control groups for age, height, body mass, gender, FXIIa, TAG, TC, HDL-C, or apo B, although the women did show significantly lower levels of TAG (p<0.04) and higher HDL-C (p<0.0001) than the men. General linear model analysis of data obtained after the intervention, using the baseline value as a covariate, showed significant reductions (p<0.0001) in FXIIa for the walkers compared with the controls. Pearson product-moment correlations also showed significant relations between the concentrations of FXIIa and TAG, TC, LDL-C, and apo B. Conclusions—The findings of this study suggest that FXIIa is sensitive to change from exercise intervention and support previous research showing an association between the concentrations of FXIIa and TAG rich lipoproteins.

The effect of match standard on objective and subjective match demands of elite soccer referees

Soccer instep kick kinematics has been examined in the literature through 2D analysis and more recently 3D analysis (Levanon and Dapena, 1998: Medicine and Science in Sports and Exercise, 30, 917–927). The importance of ball approach prior to kick execution has been recognised in other sports such as rugby (Jackson and Baker, 2001: The Sport Psychologist, 15, 48–65). However, there is limited research on the relationship between ball approach, shot accuracy and kick kinematics in soccer. The objective of this case study was to establish the effect of altering the ball approach, on kick kinematics and shot accuracy, when performing instep penalty kicks.Annual Conference of the British Association of Sport and Exercise Sciences Liverpool, 7th – 9th September 2004 PART I. BIOMECHANICS 20. Parameter determination for a torque-driven model of springboard diving takeoff P.W. Kong, M.R. Yeadon and M.A. King School of Sport and Exercise Sciences, Loughborough University, Ashby Road, Loughborough, LE11 3TU In order to develop a planar computer simulation model of a springboard and a 8-segment diver suitable for investigating diving takeoffs (Fig. 1), it is necessary to determine subject-specific model parameters. These include: 1) springboard, 2) segmental inertia, 3) strength, 4) wobbling mass, and 5) foot-springboard interface parameters. The aim of this study was to determine such parameters either directly from measurements or indirectly using an angle-driven model. Subject-specific parameters were determined from an elite female diver who provided informed consent. Testing procedures were approved by the University Ethical Advisory Committee. The vertical behaviour of the springboard was modelled as a linear mass-spring system with no damping and with stiffness as a linear function of foot placement. The stiffness and effective board mass were measured using a dynamic board loading method (Miller and Jones, 1999: Research Quarterly for Exercise and Sport, 70, 395–400). The horizontal deflection was a quadratic function of the vertical deflection and the board angle was a linear function of the vertical deflection. Body segmental inertias were calculated from 95 anthropometric measurements of the diver using a mathematical model of the human body (Yeadon, 1990: Journal of Biomechanics, 23, 67–74). To ensure that the torque generators produced realistic joint torques, maximum isometric and isovelocity torques of the diver were obtained using an isokinetic dynamometer. Movements measured included flexion and extension of shoulder, hip, knee and ankle. A 10parameter fit was used to express torque as a function of joint angle and angular velocity. Wobbling masses were included in the shank, thigh and trunk segments to model the movement of soft tissues during impact. The wobbling mass inertias were calculated from body composition and density reported in the literature and scaled to the diver. Each wobbling mass was attached to the body segment through two pairs of non-linear damped springs. Initial estimates of stiffness and damping were chosen so as to produce appropriate displacement and oscillation frequency. The elastic properties of the foot-springboard interface were represented by three pairs of spring-dampers acting on the heel, ball and toes. The stiffness and damping of these elastic elements, along with the refined estimation ofwobblingmass parameters and springboard stiffness, were determined using an angle-driven model. This was achieved by driving the model with joint angle time histories obtained from 200 Hz video recordings of diving performance from a one-metre springboard and minimising the difference in orientation and linear and angular momentum between simulation and performance using the Simulated Annealing optimisation algorithm (Corana et al., 1987: ACM Transactions on Mathematical Software, 13, 262–280). Four dives with minimum and maximum angular momentum in the Fig. 1. Simulation model of a springboard and a diver. Journal of Sports Sciences, 2005, 23, 93–223 Journal of Sports Sciences ISSN 0264-0414 print/ISSN 1466-447X online # 2005 Taylor & Francis Group Ltd DOI: 10.1080/02640410512331334413 forward and reverse groups were used to obtain a common set of parameters. The mean difference between simulation and performance was 8.3%. This paper described how subject-specific parameters could be measured experimentally or determined indirectly using an angle-driven model. These model parameters will then be used in a torque-driven model which, after satisfactory evaluation, will be used to investigate diving takeoff techniques and to optimise performance. Acknowledgment: This study was supported by the International Society of Biomechanics. 21. Strategies for maximum velocity movements in relation to reaction time and performance