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Philo U. Saunders, Christoph Ahlgrim, Brent Vallance, Daniel J. Green, Eileen Y. Robertson, Sally A. Clark, Yorck O. Schumacher and Christopher J. Gore

Purpose:

To quantify physiological and performance effects of hypoxic exposure, a training camp, the placebo effect, and a combination of these factors.

Methods:

Elite Australian and International race walkers (n = 17) were recruited, including men and women. Three groups were assigned: 1) Live High:Train Low (LHTL, n = 6) of 14 h/d at 3000 m simulated altitude; 2) Placebo (n = 6) of 14 h/d of normoxic exposure (600 m); and 3) Nocebo (n = 5) living in normoxia. All groups undertook similar training during the intervention. Physiological and performance measures included 10-min maximal treadmill distance, peak oxygen uptake (VO2peak), walking economy, and hemoglobin mass (Hbmass).

Results:

Blinding failed, so the Placebo group was a second control group aware of the treatment. All three groups improved treadmill performance by approx. 4%. Compared with Placebo, LHTL increased Hbmass by 8.6% (90% CI: 3.5 to 14.0%; P = .01, very likely), VO2peak by 2.7% (-2.2 to 7.9%; P = .34, possibly), but had no additional improvement in treadmill distance (-0.8%, -4.6 to 3.8%; P = .75, unlikely) or economy (-8.2%, -24.1 to 5.7%; P = .31, unlikely). Compared with Nocebo, LHTL increased Hbmass by 5.5% (2.5 to 8.7%; P = .01, very likely), VO2peak by 5.8% (2.3 to 9.4%; P = .02, very likely), but had no additional improvement in treadmill distance (0.3%, -1.9 to 2.5%; P = .75, possibly) and had a decrease in walking economy (-16.5%, -30.5 to 3.9%; P = .04, very likely).

Conclusion:

Overall, 3-wk LHTL simulated altitude training for 14 h/d increased Hbmass and VO2peak, but the improvement in treadmill performance was not greater than the training camp effect.

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Moritz Schumann, Javier Botella, Laura Karavirta and Keijo Häkkinen

Purpose:

To compare the effects of a standardized endurance-training program with individualized endurance training modified based on the cumulative training load provided by the Polar training-load feature.

Methods:

After 12 wk of similar training, 24 recreationally endurance-trained men were matched to a training-load-guided (TL, n = 10) or standardized (ST, n = 14) group and continued training for 12 wk. In TL, training sessions were individually chosen daily based on an estimated cumulative training load, whereas in ST the training was standardized with 4–6 sessions/wk. Endurance performance (shortest 1000-m running time during an incremental field test of 6 × 1000 m) and heart-rate variability (HRV) were measured every 4 wk, and maximal oxygen consumption (VO2max) was measured during an incremental treadmill test every 12 wk.

Results:

During weeks 1–12, similar changes in VO2max and 1000-m time were observed in TL (+7% ± 4%, P = .004 and –6% ± 4%, P = .069) and ST (+5% ± 7%, P = .019 and –8% ± 5%, P < .001). During wk 13–24, VO2max statistically increased in ST only (3% ± 4%, P = .034). The 1000-m time decreased in TL during wk 13–24 (–9% ± 5%, P = .011), but in ST only during wk 13–20 (–3% ± 2%, P = .003). The overall changes in VO2max and 1000-m time during wk 0–24 were similar in TL (+7% ± 4%, P = .001 and –9% ± 5%, P = .011) and ST (+10% ± 7%, P < .001 and –13% ± 5%, P < .001). No between-groups differences in total training volume and frequency were observed. HRV remained statistically unaltered in both groups.

Conclusions:

The main finding was that training performed according to the cumulative training load led to improvements in endurance performance similar to those with standardized endurance training in recreational endurance runners.

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Judith Allgrove, Emily Farrell, Michael Gleeson, Gary Williamson and Karen Cooper

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period every 10 min, followed by a ride to exhaustion at 90% VO2max. In the 2 wk before exercise participants consumed 40 g of DC or an isocarbohydrate-fat control cocoa liquor–free chocolate (CON) twice daily and once 2 hr before exercise in a randomized, counterbalanced, crossover design. Venous blood samples were taken immediately before exercise, postexercise (fixed duration), postexhaustion, and after 1 hr of recovery. F2-isoprostanes were significantly lower (post hoc tests: p < .001) at exhaustion and after 1 hr of recovery with DC. Oxidized low-density lipoproteins were significantly lower with DC (p < .001) both before and after exercise and at exhaustion. DC was also associated with ~21% greater rises in free fatty acids during exercise (main effect: p < .05). Changes in circulating glucose, insulin, glucagon, cortisol, and interleukin (IL)-6, IL-10, and IL-1ra were unaffected by treatment. Time to exhaustion at 90% VO2max was not significantly different between trials (398 ± 204 and 374 ± 194 s for DC and CON, respectively). These results suggest that regular DC intake is associated with reduced oxidative-stress markers and increased mobilization of free fatty acids after exercise but has no observed effect on exercise performance.

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Joana F. Reis, Gregoire P. Millet, Davide Malatesta, Belle Roels, Fabio Borrani, Veronica E. Vleck and Francisco B. Alves

Purpose:

The aim of this study was to compare VO2 kinetics during constant power cycle exercise measured using a conventional facemask (CM) or a respiratory snorkel (RS) designed for breath-by-breath analysis in swimming.

Methods:

VO2 kinetics parameters—obtained using CM or RS, in randomized counterbalanced order—were compared in 10 trained triathletes performing two submaximal heavy-intensity cycling square-wave transitions. These VO2 kinetics parameters (ie, time delay: td1, td2; time constant: τ1, τ2; amplitude: A1, A2, for the primary phase and slow component, respectively) were modeled using a double exponential function. In the case of the RS data, this model incorporated an individually determined snorkel delay (ISD).

Results:

Only td1 (8.9 ± 3.0 vs 13.8 ± 1.8 s, P < .01) differed between CM and RS, whereas all other parameters were not different (τ1 = 24.7 ± 7.6 vs 21.1 ± 6.3 s; A1 = 39.4 ± 5.3 vs 36.8 ± 5.1 mL·min−1·kg−1; td = 107.5 ± 87.4 vs 183.5 ± 75.9 s; A2' (relevant slow component amplitude) = 2.6 ± 2.4 vs 3.1 ± 2.6 mL·min−1·kg−1 for CM and RS, respectively).

Conclusions:

Although there can be a small mixture of breaths allowed by the volume of the snorkel in the transition to exercise, this does not appear to significantly influence the results. Therefore, given the use of an ISD, the RS is a valid instrument for the determination of VO2 kinetics within submaximal exercise.

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Nathan D. Dicks, Nicholas A. Jamnick, Steven R. Murray and Robert W. Pettitt

Purpose:

To investigate a new power-to-body-mass (BM) ratio 3-min all-out cycling test (3MT%BM) for determining critical power (CP) and finite work capacity above CP (W ′).

Methods:

The gas-exchange threshold (GET), maximal oxygen uptake (VO2max), and power output evoking VO2max (W peak) and GET (W GET) for cycle ergometry were determined in 12 participants. CP and W′ were determined using the original “linear factor” 3MT (3MTrpm^2) and compared with CP and W′ derived from a procedure, the 3MT%BM, using the subject’s body mass and self-reported physical activity rating (PA-R), with values derived from linear regression of the work–time model and power–inverse-time model (1/time) data from 3 separate exhaustive squarewave bouts.

Results:

The VO2max, VO2GET, W peak, and W GET values estimated from PA-R and a non-exercise-regression equation did not differ (P > .05) from actual measurements. Estimates of CP derived from the 3MT%BM (235 ± 56 W), 3MTrpm^2 (234 ± 62 W), work–time (231 ± 57 W), and 1/time models (230 ± 57 W) did not differ (F = 0.46, P = .72). Similarly, estimates of W′ between all methods did not differ (F = 3.58, P = .07). There were strong comparisons of the 3MT%BM to 1/time and work–time models with the average correlation, standard error of the measurement, and CV% for critical power being .96, 8.74 W, and 4.64%, respectively.

Conclusion:

The 3MT%BM is a valid, single-visit protocol for determining CP and W′.

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Andy Galbraith, James Hopker, Marco Cardinale, Brian Cunniffe and Louis Passfield

Purpose:

To examine the training and concomitant changes in laboratory- and field-test performance of highly trained endurance runners.

Methods:

Fourteen highly trained male endurance runners (mean ± SD maximal oxygen uptake [VO2max] 69.8 ± 6.3 mL · kg−1 · min−1) completed this 1-y training study commencing in April. During the study the runners undertook 5 laboratory tests of VO2max, lactate threshold (LT), and running economy and 9 field tests to determine critical speed (CS) and the modeled maximum distance performed above CS (D′). The data for different periods of the year were compared using repeated-measures ANOVA. The influence of training on laboratory- and field-test changes was analyzed by multiple regression.

Results:

Total training distance varied during the year and was lower in May–July (333 ± 206 km, P = .01) and July–August (339 ± 206 km, P = .02) than in the subsequent January–February period (474 ± 188 km). VO2max increased from the April baseline (4.7 ± 0.4 L/min) in October and January periods (5.0 ± 0.4 L/min, P ≤ .01). Other laboratory measures did not change. Runners’ CS was lowest in August (4.90 ± 0.32 m/s) and highest in February (4.99 ± 0.30 m/s, P = .02). Total training distance and the percentage of training time spent above LT velocity explained 33% of the variation in CS.

Conclusion:

Highly trained endurance runners achieve small but significant changes in VO2max and CS in a year. Increases in training distance and time above LT velocity were related to increases in CS.

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Martin Buchheit, Bachar Haydar, Karim Hader, Pierre Ufland and Said Ahmaidi

Purpose:

To examine physiological responses to submaximal feld running with changes of direction (COD), and to compare two approaches to assess running economy (RE) with COD, ie, during square-wave (SW) and incremental (INC) exercises.

Methods:

Ten male team-sport athletes performed, in straight-line or over 20 m shuttles, one maximal INC and four submaximal SW (45, 60, 75 and 90% of the velocity associated with maximal pulmonary O2 uptake [vVO2pmax]). Pulmonary (VO2p) and gastrocnemius (VO2m) O2 uptake were computed for all tests. For both running mode, RE was estimated as the O2 cost per kilogram of bodyweight, per meter of running during all SW and INC.

Results:

Compared with straight-line runs, shuttle runs were associated with higher VO2p (eg, 33 ± 6 vs 37 ± 5 mL O2·min–1·kg–1 at 60%, P < .01) and VO2m (eg, 1.1 ± 0.5 vs 1.3 ± 0.8 mL O2·min–1·100 g–1 at 60%, P = .18, Cohen’s d = 0.32). With COD, RE was impaired during SW (0.26 ± 0.02 vs 0.24 ± 0.03 mL O2·kg–1·m–1, P < .01) and INC (0.23 ± 0.04 vs 0.16 ± 0.03 mL O2·kg–1·m–1, P < .001). For both SW and INC tests, the changes in RE with COD were related to height (eg, r = .56 [90%CL, 0.01;0.85] for SW) and weekly training/competitive volume (eg, r = –0.58 [–0.86;–0.04] for SW). For both running modes, RE calculated from INC was better than that from SW (both P < .001).

Conclusion:

Although RE is impaired during feld running with COD, team-sport players of shorter stature and/or presenting greater training/competitive volumes may present a lower RE deterioration with COD. Present results do not support the use of INC to assess RE in the feld, irrespective of running mode.

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Stephen A. Ingham, Barry W. Fudge, Jamie S. Pringle and Andrew M. Jones

Prior high-intensity exercise increases the oxidative energy contribution to subsequent exercise and may enhance exercise tolerance. The potential impact of a high-intensity warm-up on competitive performance, however, has not been investigated.

Purpose:

To test the hypothesis that a high-intensity warm-up would speed VO2 kinetics and enhance 800-m running performance in well-trained athletes.

Methods:

Eleven highly trained middle-distance runners completed two 800-m time trials on separate days on an indoor track, preceded by 2 different warm-up procedures. The 800-m time trials were preceded by a 10-min self-paced jog and standardized mobility drills, followed by either 6 × 50-m strides (control [CON]) or 2 × 50-m strides and a continuous high-intensity 200-m run (HWU) at race pace. Blood [La] was measured before the time trials, and VO2 was measured breath by breath throughout exercise.

Results:

800-m time-trial performance was significantly faster after HWU (124.5 ± 8.3 vs CON, 125.7 ± 8.7 s, P < .05). Blood [La] was greater after HWU (3.6 ± 1.9 vs CON, 1.7 ± 0.8 mM; P < .01). The mean response time for VO2 was not different between conditions (HWU, 27 ± 6 vs CON, 28 ± 7 s), but total O2 consumed (HWU, 119 ± 18 vs CON, 109 ± 28 ml/kg, P = .05) and peak VO2 attained (HWU, 4.21 ± 0.85 vs CON, 3.91 ± 0.63 L/min; P = .08) tended to be greater after HWU.

Conclusions:

These data indicate that a sustained high-intensity warm-up enhances 800-m time-trial performance in trained athletes.

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Tom W. Macpherson and Matthew Weston

Purpose:

To examine the effect of low-volume sprint interval training (SIT) on the development (part 1) and subsequent maintenance (part 2) of aerobic fitness in soccer players.

Methods:

In part 1, 23 players from the same semiprofessional team participated in a 2-wk SIT intervention (SIT, n = 14, age 25 ± 4 y, weight 77 ± 8 kg; control, n = 9, age 27 ± 6 y, weight 72 ± 10 kg). The SIT group performed 6 training sessions of 4–6 maximal 30-s sprints, in replacement of regular aerobic training. The control group continued with their regular training. After this 2-wk intervention, the SIT group was allocated to either intervention (n = 7, 1 SIT session/wk as replacement of regular aerobic training) or control (n = 7, regular aerobic training with no SIT sessions) for a 5-wk period (part 2). Pre and post measures were the YoYo Intermittent Recovery Test Level 1 (YYIRL1) and maximal oxygen uptake (VO2max).

Results:

In part 1, the 2-week SIT intervention had a small beneficial effect on YYIRL1 (17%; 90% confidence limits ±11%), and VO2max (3.1%; ±5.0%) compared with control. In part 2, 1 SIT session/wk for 5 wk had a small beneficial effect on VO2max (4.2%; ±3.0%), with an unclear effect on YYIRL1 (8%; ±16%).

Conclusion:

Two weeks of SIT elicits small improvements in soccer players’ high-intensity intermittent-running performance and VO2max, therefore representing a worthwhile replacement of regular aerobic training. The effectiveness of SIT for maintaining SIT-induced improvements in high-intensity intermittent running requires further research.

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M. Kathleen Ellis and Lynn A. Darby

This study compared balance and peak oxygen consumption (peak VO2) among hearing, congenital nonhearing, and acquired nonhearing female intercollegiate athletes. Twenty-seven subjects completed two measures of peak VO2 and two measures of balance (static and dynamic). Two pieces of exercise equipment requiring different levels of balance were used: the bicycle ergometer (minimal balance) and the bench-step (maximal balance). Significant differences were found for dynamic balance and for peak VO2 for all subject groups. The significant difference remained among the groups for peak VO2 using the bicycle ergometer when dynamic balance was used as a covariate. There was no significant difference for peak VO2 dependent on type of test when dynamic balance was controlled. The results indicated that dynamic balance affected peak VO2 performance on the bench-step, but not on the bicycle ergometer. These findings suggest that if dynamic balance is required for an assessment of peak VO2, balance should be tested in nonhearing populations.