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Amândio M.C. Santos, Joanne R. Welsman, Mark B.A. De Ste Croix and Neil Armstrong

Age- and sex-related differences in optimal peak power (PPopt) and associated measures determined using a force-velocity (F-V) cycling test were examined in pre teenage, teenage and adult males and females. Absolute PPopt increased significantly with age in both males and females. With body mass controlled for using allometric scaling significant age related increases remained, an effect masked in the females when PPopt was expressed as W • kg−1. Sex differences in PPopt were minimal in the preteens but males demonstrated higher PPopt than females in both teenage and adult groups. These patterns of change with age and sex broadly reflect those obtained for Wingate Anaerobic Test determined PP but the use of a single non-optimized braking force underestimates the magnitude of any differences observed.

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Edward C. Frederick and John L. Hagy

Nine subjects (6 males, 3 females) ranging in body mass from 90.9 to 45.5 kg ran repeated trials across a force platform while being filmed at 50 fps. The subjects ran five barefooted trials at each of three speeds: 3.35, 3.83, and 4.47 m · s−1. Force data were collected on-line and analyzed for the magnitude and temporal characteristics of the initial impact (Fz1) peak and the active (Fz2) peak of vertical ground reaction force (VGRF). Multiple regression and correlation analysis were used to study the relationship between the magnitudes of these kinetic data and kinematic and anthropometric data taken from the film and from measurements of the subjects. The results support the general conclusion that speed and, indirectly, body mass are significant effectors of the magnitudes of Fz1. In addition, other factors that correlate significantly with Fz1 are reciprocal ponderal index (RPI) and stature; half-stride length, step length, leg length, and vertical hip excursion during a half-stride cycle; and hip offset, contact angle, and dorsiflexion angle at contact. Body mass correlates highly with Fz2 (r = 0.95). Other significant factors correlating with Fz2 are RPI, stature, vertical hip excursion, dorsiflexion angle, hip offset, half-stride length, and step length. These data support earlier findings that speed and the effective mass of the leg at contact are important effectors of the magnitude of Fzl. In addition, the kinematic and anthropometric parameters that contribute significantly to the variability in Fzl and F are generally cross-correlated with body size and/or running speed.

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Andrea Monte, Francesca Nardello and Paola Zamparo

Purpose:

The effects of different loads on kinematic and kinetic variables during sled towing were investigated with the aim to identify the optimal overload for this specific sprint training.

Methods:

Thirteen male sprinters (100-m personal best: 10.91 ± 0.14 s) performed 5 maximal trials over a 20-m distance in the following conditions: unloaded and with loads from 15% to 40% of the athlete’s body mass (BM). In these calculations the sled mass and friction were taken into account. Contact and flight times, stride length, horizontal hip velocity (vh), and relative angles of hip, knee, and ankle (at touchdown and takeoff) were measured step by step. In addition, the horizontal force (Fh) and power (Ph) and maximal force (Fh0) and power (Ph0) were calculated.

Results:

vh, flight time, and step length decreased while contact time increased with increasing load (P < .001). These variables changed significantly also as a function of the step number (P < .01), except between the 2 last steps. No differences were observed in Fh among loads, but Fh was larger in sled towing than in unloaded. Ph was unaffected by load up to +20%BM but decreased with larger loads. Fh0 and Ph0 were achieved at 20%BM. Up to 20%BM, no significant effects on joint angles were observed at touchdown and takeoff, while at loads >30%BM joint angles tended to decrease.

Conclusion:

The 20%BM condition represents the optimal overload for peak power production—at this load sprinters reach their highest power without significant changes in their running technique (eg, joint angles).

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Barbara E. Ainsworth, Robert G. McMurray and Susan K. Veazey

The purpose of this study was to determine the accuracy of two submaximal exercise tests, the Sitting-Chair Step Test (Smith & Gilligan. 1983) and the Modified Step Test (Amundsen, DeVahl, & Ellingham, 1989) to predict peak oxygen uptake (VO2 peak) in 28 adults ages 60 to 85 years. VO2 peak was measured by indirect calorimetry during a treadmill maximal graded exercise test (VO2 peak, range 11.6–31.1 ml · kg −l · min−1). In each of the submaximal tests, VO2 was predicted by plotting stage-by-stage submaximal heart rate (HR) and perceived exertion (RPE) data against VO2 for each stage and extrapolating the data to respective age-predicted maximal HR or RPE values. In the Sitting-Chair Step Test (n = 23), no significant differences were observed between measured and predicted VO2 peak values (p > .05). However, predicted VO2 peak values from the HR were 4.3 ml · kg−1 · min−1 higher than VO2 peak values predicted from the RPE data (p < .05). In the Modified Step Test (n = 22), no significant differences were observed between measured and predicted VO2 peak values (p > .05). Predictive accuracy was modest, explaining 49–78% of the variance in VO2 peak. These data suggest that the Sitting-Chair Step Test and the Modified Step Test have moderate validity in predicting VO2 peak in older men and women.

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Ashleigh E. Smith, Roger G. Eston, Belinda Norton and Gaynor Parfitt

Peak oxygen uptake (V̇O2peak) is reliably predicted in young and middle-aged adults using a submaximal perceptually-regulated exercise test (PRET). It is unknown whether older adults can use a PRET to accurately predict V̇O2peak. In this study, the validity of a treadmill-based PRET to predict V̇O2peak was assessed in 24 participants (65.2 ± 3.9 years, 11 males). The PRET required a change in speed or incline corresponding to ratings of perceived exertion (RPE) 9, 11, 13, and 15. Extrapolation of submaximal V̇O2 from the PRET to RPE endpoints 19 and 20 and age-predicted HRmax were compared with measured V̇O2peak. The V̇O2 extrapolated to both RPE19 and 20 over-predicted V̇O2peak (p < .001). However, extrapolating V̇O2 to age-predicted HRmax accurately predicted V̇O2peak (r = .84). Results indicate older adults can use a PRET to predict V̇O2peak by extrapolating V̇O2 from submaximal intensities to an age-predicted HRmax.

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Peter Pfitzinger and Patty Freedson

Part 1 reviews the literature concerning peak blood lactate responses to exercise in children. After a brief overview of lactate metabolism, an analysis is presented comparing children to adults regarding peak blood lactate concentration. Possible factors accounting for lower blood lactate concentrations during maximal exercise in children are considered.

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Minsoo Kang, Youngdeok Kim and David A. Rowe

Background:

This study examined the optimal measurement conditions to obtain reliable peak cadence measures using the accelerometer-determined step data from the National Health and Nutrition Examination Survey 2005–2006.

Methods:

A total of 1282 adults (> 17 years) who provided valid accelerometer data for 7 consecutive days were included. The peak 1- and 30-minute cadences were extracted. The sources of variance in peak stepping cadences were estimated using Generalizability theory analysis. A simulation analysis was conducted to examine the effect of the inclusion of weekend days. The optimal number of monitoring days to achieve 80% reliability for peak stepping cadences were estimated.

Results:

Intraindividual variability was the largest variance component of peak cadences for young and middle-aged adults aged < 60 years (50.55%–59.24%) compared with older adults aged ≥ 60 years (31.62%–41.72%). In general, the minimum of 7 and 5 days of monitoring were required for peak 1- and 30-minute cadences among young and middle-aged adults, respectively, whereas 3 days of monitoring was sufficient for older adults to achieve the desired reliability (0.80). The inclusion of weekend days in the monitoring frame may not be practically important.

Conclusions:

The findings could be applied in future research as the reference measurement conditions for peak cadences.

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Jane C. Golden, Kathleen F. Janz, William R. Clarke and Larry T. Mahoney

This paper demonstrates the reliability, validity, and practical applications of a unique protocol developed to obtain both submaximal steady-state and peak exercise responses in the same test in children and adolescents. The study examined exercise efficiency, cardiovascular fitness, and cardiovascular responses in 237 children, ages 7 to 17, during exercise stress on a cycle ergometer. The graded exercise test was continuous, consisting of three steady-state submaximal stages followed by 30-sec ramp stages to obtain peak values. Intraclass correlation coefficients ranged from r=0.69 to r=0.99, with no significant mean difference for any test parameter. Mean peak heart rate, peak VO2, and 84% of the respiratory exchange ratio (RER) values equal to or greater than 1.1 were comparable to other reported values. The validity for the protocol is substantiated by the results showing normal linear exercise responses, nonsignificant mean difference between the last two 30-sec periods, normal mean peak heart rate and VO2 values, and high mean peak RER values. The protocol is practical, as demonstrated by an optimal test duration and the ability to obtain valid submaximal and peak exercise data in the same test in subjects of varying ages and body size.

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Saul R. Bloxham, Joanne R. Welsman and Neil Armstrong

This study examined ergometer-specific relationships between short-term power and peak oxygen uptake (peak VO2) in children. Boys (n = 28) and girls (n = 28) age 11-12 years completed two incremental tests to exhaustion on a cycle ergometer and motorized treadmill for the determination of peak VO2. In addition, they completed two 30 s “all-out” sprint tests, one on a cycle ergometer and one on a nonmotorized treadmill for the assessment of peak power (PP) and mean power (MP). Relationships between peak VO2 and shortterm power measures were examined by sex for cycle- and treadmill-derived data using simple per-body-mass ratios and sample-specific allometric exponents to control for body size differences. From correlational analyses on scaled data, sex differences in responses were shown. In boys, PP and MP were unrelated to peak VO2 for cycle-derived measures but significantly related (r = 0.58 PP; r = 0.69 MP) for treadmill values. PP and MP were significantly related to peak VO2 for both modes of exercise in girls (r = .41−.68). In all but one case, correlation coefficients based on mass-related data were higher than those based on allometrically adjusted data.

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Juliane R. Fenster, Patty S. Freedson, Richard A. Washburn and R. Curtis Ellison

The relationship between physical activity measured using the LSI (Large Scale Integrated Activity Monitor), and questionnaire, with physical work capacity 170 (PWC 170) and aerobic capacity (peak V̇O2) was evaluated in 6- to 8-year-old children (n = 18). The mean (± SD) peak V̇O2 was 44.1 ± 5.6 ml • kg−1 • min−1. Peak V̇O2 was not significantly different for children (n = 8) who had completed two treadmill trials (45.4 vs. 43.5 ml • kg−1 • min−1; R = 0.67, p<0.05). The log LSI expressed as counts per hour (M ± SD = 2.1 ±.22 cts/hr) was the only activity method significantly related to peak V̇O2 (r = 0.59, p<0.05). The correlation between peak V̇O2 with the questionnaire was positive but nonsignificant (r = 0.20). PWC 170 was not related to peak V̇O2 (r = 0.21) or the activity variables (r = 0.12 questionnaire; r = 0.18 log LSI). When the group was divided into high and low peak V̇O2 groups (high: M = 48.8 ml • kg−1 • min−1; low: M = 39.5 ml • kg−1 • min−1), the log LSI was able to distinguish significant differences in activity levels (high: 2.23 ±. 19 cts/hr; low: 1.99±.19 cts/hr). This study suggests that activity measured with the LSI and aerobic capacity are related in this sample of 6- to 8-year-old children.