Validation of a single-stage submaximal treadmill walking test

Abstract

The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption ([Vdot]O_2max) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts [Vdot]O_2max at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 – 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of [Vdot]O_2max (low-intensity trial: mean 40.5 ml · kg^?1 · min^?1, s = 9.3; high-intensity trial: 47.5 ml · kg^?1 · min^?1, s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a [Vdot]O_2max test (mean 47.9 ml · kg^?1 · min^?1, s = 8.9). The low-intensity trial underestimated (mean difference = ?3.5 ml · kg^?1 · min^?1; 95% CI = ?6.4 to ?0.6 ml · kg^?1 · min^?1; P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml · kg^?1 · min^?1; 95% CI = 1.1 to 6.0 ml · kg^?1 · min^?1; P = 0.01) the measured [Vdot]O_2max. The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range.     

Effect of biological maturation on maximal oxygen uptake and ventilatory thresholds in soccer players: An allometric approach

Abstract

In this study, we investigated the effect of biological maturation on maximal oxygen uptake ([Vdot]O_2max) and ventilatory thresholds (VT₁ and VT₂) in 110 young soccer players separated into pubescent and post-pubescent groups.. Maximal oxygen uptake and [Vdot]O₂ corresponding to VT₁ and VT₂ were expressed as absolute values, ratio standards, theoretical exponents, and experimentally observed exponents. Absolute [Vdot]O₂ (ml · min^?1) was different between groups for VT₁, VT₂, and [Vdot]O_2max. Ratio standards (ml · kg^?1 · min^?1) were not significantly different between groups for VT₁, VT₂, and [Vdot]O_2max. Theoretical exponents (ml · kg^?0.67 · min^?1 and ml · kg^?0.75 · min^?1) were not properly adjusted for the body mass effects on VT₁, VT₂, and [Vdot]O_2max. When the data were correctly adjusted using experimentally observed exponents, VT₁ (ml · kg^?0.94 · min^?1) and VT₂ (ml · kg^?0.95 · min^?1) were not different between groups. The experimentally observed exponent for [Vdot]O_2max (ml · kg^?0.90 · min^?1) was different between groups (P = 0.048); however, this difference could not be attributed to biological maturation. In conclusion, biological maturation had no effect on VT₁, VT₂ or [Vdot]O_2max when the effect of body mass was adjusted by experimentally observed exponents. Thus, when evaluating the physiological performance of young soccer players, allometric scaling needs to be taken into account instead of using theoretical approaches.     

Maximal oxygen uptake versus maximal power output in children

Abstract

Maximal oxygen uptake ([Vdot]O_2max) is considered the optimal method to assess aerobic fitness. The measurement of [Vdot]O_2max, however, requires special equipment and training. Maximal exercise testing with determination of maximal power output offers a more simple approach. This study explores the relationship between [Vdot]O_2max and maximal power output in 247 children (139 boys and 108 girls) aged 7.9–11.1 years. Maximal oxygen uptake was measured by indirect calorimetry during a maximal ergometer exercise test with an initial workload of 30 W and 15 W · min^?1 increments. Maximal power output was also measured. A sample (n = 124) was used to calculate reference equations, which were then validated using another sample (n = 123). The linear reference equation for both sexes combined was: [Vdot]O_2max (ml · min^?1) = 96 + 10.6 · maximal power + 3.5 · body mass. Using this reference equation, estimated [Vdot]O_2max per unit of body mass (ml · min^?1 · kg^?1) calculated from maximal power correlated closely with the direct measurement of [Vdot]O_2max (r = 0.91, P <0.001). Bland-Altman analysis gave a mean limits of agreement of 0.2±2.9 (ml · min^?1 · kg^?1) (1 s). Our results suggest that maximal power output serves as a good surrogate measurement for [Vdot]O_2max in population studies of children aged 8–11 years.     

Criterion-related validity of the 20-m shuttle run test in youths aged 13–19 years

Abstract

We assessed the agreement between maximal oxygen consumption ([Vdot]O_2max) measured directly when performing the 20-m shuttle run test and estimated [Vdot]O_2max from five different equations (i.e. Barnett, equations a and b; Léger; Matsuzaka; and Ruiz) in youths. The 20-m shuttle run test was performed by 26 girls (mean age 14.6 years, s = 1.5; body mass 57.2 kg, s = 8.9; height 1.60 m, s = 0.06) and 22 boys (age 15.0 years, s = 1.6; body mass 63.5 kg, s = 11.5; height 1.70 m, s = 0.01). The participants wore a portable gas analyser (K4b2, Cosmed) to measure [Vdot]O₂ during the test. All the equations significantly underestimated directly measured [Vdot]O_2max, except Barnett's (b) equation. The mean difference ranged from 1.3 ml · kg^?1 · min^?1 (Barnett (b)) to 5.5 ml · kg^?1 · min^?1 (Léger). The standard error of the estimate ranged from 5.3 ml · kg^?1 · min^?1 (Ruiz) to 6.5 ml · kg^?1 · min^?1 (Léger), and the percentage error ranged from 21.2% (Ruiz) to 38.3% (Léger). The accuracy of the equations available to estimate [Vdot]O_2max from the 20-m shuttle run test is questionable at the individual level. Furthermore, special attention should be paid when comparisons are made between studies (e.g. population-based studies) using different equations. The results of the present study suggest that Barnett's (b) equation provides the closest agreement with directly measured [Vdot]O_2max (cardiorespiratory fitness) in youth.     

The multi-stage fitness test as a predictor of endurance fitness in wheelchair athletes

Abstract

The aims of this study were two-fold: (1) to consider the criterion-related validity of the multi-stage fitness test (MSFT) by comparing the predicted maximal oxygen uptake ([Vdot]O_2max) and distance travelled with peak oxygen uptake ([Vdot]O_2peak) measured using a wheelchair ergometer (n = 24); and (2) to assess the reliability of the MSFT in a sub-sample of wheelchair athletes (n = 10) measured on two occasions. Twenty-four trained male wheelchair basketball players (mean age 29 years, s = 6) took part in the study. All participants performed a continuous incremental wheelchair ergometer test to volitional exhaustion to determine [Vdot]O_2peak, and the MSFT on an indoor wooden basketball court. Mean ergometer [Vdot]O_2peak was 2.66 litres · min^?1 (s = 0.49) and peak heart rate was 188 beats · min^?1 (s = 10). The group mean MSFT distance travelled was 2056 m (s = 272) and mean peak heart rate was 186 beats · min^?1 (s = 11). Low to moderate correlations (ρ = 0.39 to 0.58; 95% confidence interval [CI]: ?0.02 to 0.69 and 0.23 to 0.80) were found between distance travelled in the MSFT and different expressions of wheelchair ergometer [Vdot]O_2peak. There was a mean bias of ?1.9 beats · min^?1 (95% CI: ?5.9 to 2.0) and standard error of measurement of 6.6 beats · min^?1 (95% CI: 5.4 to 8.8) between the ergometer and MSFT peak heart rates. A similar comparison of ergometer and predicted MSFT [Vdot]O_2peak values revealed a large mean systematic bias of 15.3 ml · kg^?1 · min^?1 (95% CI: 13.2 to 17.4) and standard error of measurement of 3.5 ml · kg^?1 · min^?1 (95% CI: 2.8 to 4.6). Small standard errors of measurement for MSFT distance travelled (86 m; 95% CI: 59 to 157) and MSFT peak heart rate (2.4 beats · min^?1; 95% CI: 1.7 to 4.5) suggest that these variables can be measured reliably. The results suggest that the multi-stage fitness test provides reliable data with this population, but does not fully reflect the aerobic capacity of wheelchair athletes directly.     

Similar results for face mask versus mouthpiece during incremental exercise to exhaustion

Investigations in the 1990s evaluated the influence of breathing assemblies on respiratory variables at rest and during exercise; however, research on new models of breathing assemblies is lacking. This study compared metabolic gas analysis data from a mouthpiece with a noseclip (MOUTH) and a face mask (MASK). Volunteers (7 males, 7 females; 25.1 ± 2.7 years) completed two maximal treadmill tests within 1 week, one MOUTH and one MASK, in random order. The difference in maximal oxygen consumption (VO_2max) between MOUTH (52.7 ± 11.3 ml · kg^?1 · min^?1) and MASK (52.2 ± 11.7 ml · kg^?1 · min^?1) was not significant (P = 0.53). Likewise, the mean MOUTH–MASK differences in minute ventilation (V_E), fraction of expired oxygen (FEO₂) and carbon dioxide (FECO₂), respiration rate (RR), tidal volume (V_t), heart rate (HR), and rating of perceived exertion (RPE) at maximal and submaximal intensities were not significant (P > 0.05). Furthermore, there was no systematic bias in the error scores (r = ?0.13, P = 0.66), and 12 of the 14 participants had a VO_2max difference of ≤3 ml · kg^?1 · min^?1 between conditions. Finally, there was no clear participant preference for using the MOUTH or MASK. Selection of MOUTH or MASK will not affect the participant’s gas exchange or breathing patterns.     

Maximum oxygen uptake and body composition of healthy Hong Kong Chinese adult men and women aged 20 – 64 years

Abstract

The aims of the present study were to assess the maximal oxygen uptake and body composition of adult Chinese men and women, and to determine how these variables relate to age. The cross-sectional sample consisted of 196 men and 221 women aged 20 – 64 years. Maximal oxygen uptake ([Vdot]O_2max) was determined by indirect calorimetry during a maximal exercise test on an electrically braked cycle ergometer. The correlations between [Vdot]O_2max and fat mass were ?0.52 in men and ?0.58 in women. Linear regression defined the cross-sectional age-related decline in [Vdot]O_2max as 0.35 ml · kg^?1 · min^?1 · year^?1 in men and 0.30 ml · kg^?1 · min^?1 · year^?1 in women. Multiple regression analysis showed that more than 50% of this cross-sectional decline in [Vdot]O_2max was due to fat mass, lean mass, and age. Adding fat mass and lean mass to the multiple regression models reduced the age regression mass from 0.35 to 0.24 ml · kg^?1 · min^?1 · year^?1 in men and from 0.30 to 0.15 ml · kg^?1 · min^?1 · year^?1 in women. We conclude that age, fat mass, and lean mass are independent determinants of maximal oxygen uptake in Chinese adults.     

Chronic ingestion of a low dose of caffeine induces tolerance to the performance benefits of caffeine

This study examined effects of 4 weeks of caffeine supplementation on endurance performance. Eighteen low-habitual caffeine consumers (<75 mg · day^?1) were randomly assigned to ingest caffeine (1.5–3.0 mg · kg^?1day^?1; titrated) or placebo for 28 days. Groups were matched for age, body mass, V?O_2peak and W_max (P > 0.05). Before supplementation, all participants completed one V?O_2peak test, one practice trial and 2 experimental trials (acute 3 mg · kg^?1 caffeine [precaf] and placebo [testpla]). During the supplementation period a second V?O_2peak test was completed on day 21 before a final, acute 3 mg · kg^?1 caffeine trial (postcaf) on day 29. Trials consisted of 60 min cycle exercise at 60% V?O_2peak followed by a 30 min performance task. All participants produced more external work during the precaf trial than testpla, with increases in the caffeine (383.3 ± 75 kJ vs. 344.9 ± 80.3 kJ; Cohen’s d effect size [ES] = 0.49; P = 0.001) and placebo (354.5 ± 55.2 kJ vs. 333.1 ± 56.4 kJ; ES = 0.38; P = 0.004) supplementation group, respectively. This performance benefit was no longer apparent after 4 weeks of caffeine supplementation (precaf: 383.3 ± 75.0 kJ vs. postcaf: 358.0 ± 89.8 kJ; ES = 0.31; P = 0.025), but was retained in the placebo group (precaf: 354.5 ± 55.2 kJ vs. postcaf: 351.8 ± 49.4 kJ; ES = 0.05; P > 0.05). Circulating caffeine, hormonal concentrations and substrate oxidation did not differ between groups (all P > 0.05). Chronic ingestion of a low dose of caffeine develops tolerance in low-caffeine consumers. Therefore, individuals with low-habitual intakes should refrain from chronic caffeine supplementation to maximise performance benefits from acute caffeine ingestion.     

Metabolic cost of running is greater on a treadmill with a stiffer running platform

Exercise testing on motorised treadmills provides valuable information about running performance and metabolism; however, the impact of treadmill type on these tests has not been investigated. This study compared the energy demand of running on two laboratory treadmills: an HP Cosmos (C) and a Quinton (Q) model, with the latter having a 4.5 times stiffer running platform. Twelve experienced runners ran identical bouts on these treadmills at a range of four submaximal velocities (reported data is for the velocity that approximated 75–81% VO_2max). The stiffer treadmill elicited higher oxygen consumption (C: 46.7 ± 3.8; Q: 50.1 ± 4.3 ml·kg^?1 · min^?1), energy expenditure (C: 16.0 ± 2.5; Q: 17.7 ± 2.9 kcal · min^?1), carbohydrate oxidation (C: 9.6 ± 3.1; Q: 13.0 ± 3.9 kcal · min^?1), heart rate (C: 155 ± 16; Q: 163 ± 16 beats · min^?1) and rating of perceived exertion (C: 13.8 ± 1.2; Q: 14.7 ± 1.2), but lower fat oxidation (C: 6.4 ± 2.3; Q: 4.6 ± 2.5 kcal · min^?1) (all analysis of variance treadmill comparisons P < 0.01). This study confirms that caution is required when comparing performance and metabolic results between different treadmills and suggests that treadmills will vary in their comparability to over-ground running depending on the running platform stiffness.     

The respiratory time and flow profile at volitional exercise termination

Abstract

In this study, we examine the effect of exercise on the time and flow characteristics of the respiratory cycle profile at the point of volitional exercise termination. Eight males (mean age 29 years, s = 10; body mass 74 kg, s = 7; height 1.75 m, s = 0.04) undertook a cycle test to volitional exhaustion on a cycle ergometer, which allowed peak oxygen uptake ([Vdot]O_2peak) to be measured (mean 51 ml · kg^?1 · min^?1, s = 7). At a later date, two sub-maximal tests to volitional exhaustion were completed in a random order at 76% (s = 6) and 86%[Vdot]O_2peak (s = 7). As expected, the magnitude of the respiratory flow and time characteristics varied with the three exercise intensities, as did the point of exercise termination and terminal ventilation rates, which varied from 7 to 27 min and 112 to 132 litres · min^?1 respectively. More importantly, however, at exercise termination some of the characteristics were similar, particularly the breathing frequency (at termination 49 breaths · min^?1), the ratio between inspiration and total breath time (0.5), and the later occurrence of peak inspiratory flow (0.24 – 0.48 s). The coincident unity of these time and flow profile characteristics at exercise termination illustrates how the integration of timing and flow during breathing influence exercise capacity in non-elite athletes.     

Effect of suspension systems on the physiological and psychological responses to sub-maximal biking on simulated smoothand bumpy tracks

Abstract

The aim of this study was to compare the physiological and psychological responses of cyclists riding on a hard tail bicycle and on a full suspension bicycle. Twenty males participated in two series of tests. A test rig held the front axle of the bicycle steady while the rear wheel rotated against a heavy roller with bumps (or no bumps) on its surface. In the first series of tests, eight participants (age 19 – 27 years, body mass 65 – 82 kg) were tested on both the full suspension and hard tail bicycles with and without bumps fitted to the roller. The second series of test repeated the bump tests with a further six participants (age 22 – 31 years, body mass 74 – 94 kg) and also involved an investigation of familiarization effects with the final six participants (age 21 – 30 years, body mass 64 – 80 kg). Heart rate, oxygen consumption ([Vdot]O₂), rating of perceived exertion (RPE) and comfort were recorded during 10 min sub-maximal tests. Combined data for the bumps tests show that the full suspension bicycle was significantly different (P < 0.001) from the hard tail bicycle on all four measures. Oxygen consumption, heart rate and RPE were lower on average by 8.7 (s = 3.6) ml · kg^?1 · min^?1, 32.1 (s = 12.1) beats · min^?1 and 2.6 (s = 2.0) units, respectively. Comfort scores were higher (better) on average by 1.9 (s = 0.8) units. For the no bumps tests, the only statistically significant difference (P = 0.008) was in [Vdot]O₂, which was lower for the hard tail bicycle by 2.2 (s = 1.7) ml · kg^?1 · min^?1. The results indicate that the full suspension bicycle provides a physiological and psychological advantage over the hard tail bicycle during simulated sub-maximal exercise on bumps.     

Effect of a carbohydrate mouthwash on running time-trial performance

Abstract

The aim of the present study was to determine the effect of a carbohydrate mouthwash on running time-trial performance. On two separate occasions, seven recreationally active males ([Vdot]O_2max 57.8 ml · kg^?1 · min^?1, s = 3.7) completed a preloaded (15 min at 65%[Vdot]O_2max) time-trial of 45 min in duration on a motorized treadmill. At 6-min intervals during the preload and time-trial, participants were given either a 6% maltodextrin, 3% lemon juice solution (carbohydrate trial) or a 3% lemon juice placebo mouthwash (placebo trial) in a double-blind, randomized crossover design. Heart rate, oxygen consumption ([Vdot]O₂), respiratory exchange ratio (RER), and ratings of perceived exertion (RPE) were measured during the preload, and blood glucose and lactate were measured before and after the preload and time-trial. There were no significant differences in distance covered between trials (carbohydrate: 9333 m, s = 988; placebo: 9309 m, s = 993). Furthermore, there were no significant between-trial differences in heart rate and running speed during the time-trial, or [Vdot]O₂, RER or RPE during the preload. Blood lactate and glucose increased as a result of the exercise protocol, with no between-trial differences. In conclusion, there was no positive effect of a carbohydrate mouthwash on running performance of ～1 h duration.     

Repeatability of scores on a novel test of endurance running performance

Abstract

The aim of the present study was to determine the repeatability of a running endurance test using an automated treadmill system that requires no manual input to control running speed. On three separate occasions, 7 days apart, 10 experienced male endurance-trained runners (mean age 32 years, s = 10; [Vdot]O_2peak 61 ml · kg^?1 · min^?1, s = 7) completed a treadmill time trial, in which they were instructed to run as far as possible in 60 min. The treadmill was instrumented with an ultrasonic feedback-controlled radar modulator that spontaneously regulated treadmill belt speed corresponding to the changing running speed of each runner. Estimated running intensity was 70%[Vdot]O_2peak (s = 11) and the distance covered 13.5 km (s = 2), with no difference in mean performances between trials. The coefficient of variation, estimated using analysis of variance, with participant and trial as main effects, was 1.4%. In summary, the use of an automated treadmill system improved the repeatability of a 60-min treadmill time trial compared with time trials in which speed is controlled manually. The present protocol is a reliable method of assessing endurance performance in endurance-trained runners.     

The effects of acute carbohydrate and caffeine feeding strategies on cycling efficiency

To assess the effect of carbohydrate and caffeine on gross efficiency (GE), 14 cyclists (V?O_2max 57.6 ± 6.3 ml.kg^?1.min^?1) completed 4 × 2-hour tests at a submaximal exercise intensity (60% Maximal Minute Power). Using a randomized, counter-balanced crossover design, participants consumed a standardised diet in the 3-days preceding each test and subsequently ingested either caffeine (CAF), carbohydrate (CHO), caffeine+carbohydrate (CAF+CHO) or water (W) during exercise whilst GE and plasma glucose were assessed at regular intervals (~30 mins). GE progressively decreased in the W condition but, whilst caffeine had no effect, this was significantly attenuated in both trials that involved carbohydrate feedings (W = ?1.78 ± 0.31%; CHO = ?0.70 ± 0.25%, p = 0.008; CAF+CHO = ?0.63 ± 0.27%, p = 0.023; CAF = ?1.12 ± 0.24%, p = 0.077). Blood glucose levels were significantly higher in carbohydrate ingestion conditions (CHO = 4.79 ± 0.67 mmol·L^?1, p < 0.001; CAF+CHO = 5.05 ± 0.81 mmol·L^?1, p < 0.001; CAF = 4.46 ± 0.75 mmol·L^?1; W = 4.20 ± 0.53 mmol·L^?1). Carbohydrate ingestion has a small but significant effect on exercise-induced reductions in GE, indicating that cyclists’ feeding strategy should be carefully monitored prior to and during assessment.     

Effects of heat acclimation on hand cooling efficacy following exercise in the heat

This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO₂ max], 54.1 ± 1.3 ml·kg^?1·min^?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO₂ max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO₂ max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min^?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min^?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min^?1) was similar to NC (0.025 ± 0.002°C·min^?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min^?1) was similar to when NHA (0.020 ± 0.003°C·min^?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.     

Movement pattern and physiological response in recreational small-sided football – effect of number of players with a fixed pitch size

Recreational soccer is an effective health-promoting activity, but it is unclear how different game formats influence internal and external load. Thus, to be able to advise how to maximise the outcome of recreational football, we examined movement pattern and physiological response in 11 untrained men (32.6 ± 6.7 yrs, 23.3 ± 4.9 fat%, 43.4 ± 5.3 ml·min^?1·kg^?1) during three football sessions comprising 4 × 12 min of 3v3, 5v5 or 7v7 with a constant pitch size of 20 × 40 m. Movement pattern, heart rate (HR), blood lactate and RPE were measured during and after the 12-min periods. Greater (P < 0.05) total distance and high-speed distance was covered during 3v3 than 5v5 (14 and 30%) and 7v7 (15 and 75%). Mean HR was higher in 3v3 (85.7 ± 5.7%HRmax) and 5v5 (84.2 ± 5.1%HRmax) than in 7v7 (80.7 ± 4.6%HRmax, P < 0.05) and percentage time >90%HR was higher in 3v3 (43 ± 18%, P < 0.05) than in 5v5 (28 ± 21%) and 7v7 (18 ± 14%). Blood lactate was higher in 3v3 (7.4 ± 2.7 mmol·l^?1) than in 7v7 (4.5 ± 2.2 mmol·l^?1, P < 0.001) but not in 5v5 (6.1 ± 2.1 mmol·l^?1, P = 0.061). RPE was higher in 3v3 (6.7 ± 2.3, P < 0.01) than in 5v5 (5.2 ± 2.2) and 7v7 (4.3 ± 2.3). In conclusion, higher external and internal load was found with fewer players, when the pitch size is fixed.     

Soccer and Zumba as health-promoting activities among female hospital employees: a 40-weeks cluster randomised intervention study

Abstract

The aim of this study was to evaluate the physiological effects of soccer and Zumba among female hospital employees during a 40-week intervention period. Hospital employees (n = 118) were cluster-randomised to either a soccer group (n = 41), a Zumba group (n = 38) or a control group (n = 39). Both training groups were encouraged to perform 1-h training sessions twice a week outside working hours throughout the 40 weeks. Maximal oxygen uptake (VO₂ max), blood pressure and body composition were measured and blood samples collected before and after the intervention period. Using intention-to-treat analyses, the Zumba group improved VO₂ max compared to the control group (2.2 mL · kg^?1 · min^?1, 95% CI, 0.9, 3.5, P = 0.001), with no significant increase in the soccer group (1.1 mL · kg^?1 · min^?1, 95% CI, ?0.2, 2.4, P = 0.08). Both intervention groups reduced total body fat mass and fat percentage compared to the control group (P < 0.01). In the soccer group, but not the Zumba group, a significant difference in lower limb bone mineral density and bone mineral content was observed in comparison to the control group (P < 0.01). Furthermore, the soccer group, but not the Zumba group, had increased plasma osteocalcin (6.6 µg · L^?1, 95% CI, 2.2, 11.0, P < 0.01) and decreased plasma leptin (?6.6 µg · L^?1, 95% CI, ?12.5, ?0.7, P < 0.05) compared to the control group. The present study suggests that workplace-initiated soccer and Zumba training comprising 1–2 sessions per week outside working hours may promote physiological health among female hospital employees.     

Short-term performance peaking in an elite cross-country mountain biker

ABSTRACT

Endurance athletes usually achieve performance peaks with 2–4 weeks of overload training followed by 1–3weeks of tapering. With a tight competition schedule, this may not be appropriate. This case investigates the effect of a 7-day overload period including daily high-intensity aerobic training followed by a 5-day step taper between two competitions in an elite cross-country mountain biker. Pre-test peak oxygen consumption was 89 ml·kg^?1·min^?1, peak aerobic power 6.8 W·kg^?1, power output at 2 mmol·L^?1 blood lactate concentration 3.9 W·kg^?1, maximal isometric force 180 Nm and squat jump 21 cm. During overload, perceived leg well-being went from normal to very heavy. On day 1 after overload, vastus lateralis and vastus medialis EMG_mean activity was reduced by 3% and 7%, respectively. Other baseline measurements were reduced by 3–7%. On day 4 of the taper, he felt that his legs were good and all measurements were 3–7% higher than before overload. On day 6 after the taper, his legs felt very good. This case shows that an elite mountain biker (11th in UCI World Cup one week prior to the pre-test) could achieve a rather large supercompensation by using a 12-day performance peaking protocol.     

Development of 1-mile walk tests to estimate aerobic fitness in children

To examine the reliability and validity of 1-mile walk tests for estimation of aerobic fitness (VO_2max) in 10- to 13-year-old children and to cross-validate previously published equations. Participants (n = 61) walked 1-mile on two different days. Self-reported physical activity, demographic variables, and aerobic fitness were used in multiple regression analyses. Eight models were developed with various combinations of predictors. The recommended model for fitness testing in schools was: VO_2max = 120.702 + (4.114 × Sex [F = 0, M = 1]) – (2.918 × 1-mile Walk Time [min]) – (2.841 × Age), R = .73, standard error of estimate = 6.36 mL·kg^?1·min^?1. Cross-validation of previously published equations demonstrated lower correlations with measured VO_2max than the newly developed walk tests. Evidence of reliability and validity for 1-mile walk tests to estimate VO_2max in young children was provided. The model that included 1-mile walk time, age, and sex may be appropriate for youth fitness testing in physical education, particularly for unmotivated or overweight young children.