Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exercise performance. The value of IPC for improving performance is controversial owing to challenges with employing effective placebo controls. This study examines the efficacy of IPC versus a deceptive sham protocol for improving performance to determine whether benefits of IPC are attributable to true physiological effects. It was hypothesized that IPC would favorably alter performance more than a sham treatment and that physiological responses to exercise would be affected only after IPC treatment. Methods: In a randomized order, 16 participants performed incremental exercise to exhaustion on a cycle ergometer in control conditions and after sham and IPC treatments. Participants rated their belief as to the efficacy of each treatment compared with control. Results: Time to exhaustion was greatest after IPC (control = 1331  s, IPC = 1429  s, sham = 1343  s, P = .02), despite negative performance expectations after IPC and positive expectation after sham. Maximal aerobic power remained unchanged after both SHAM and IPC (control = 42.0 [5.2], IPC = 41.7 [5.5], sham = 41.6 [5.5] mL·kg−1·min−1, P = .7), as did submaximal lactate concentration (control = 8.9 [2.6], sham = 8.0 [1.9], IPC = 7.7 [2.1] mmol, P = .1) and oxygen uptake (control = 37.8 [4.8], sham = 37.5 [5.3], IPC = 37.5 [5.5] mL·kg−1·min−1, P = .6). Conclusions: IPC before cycling exercise provides an ergogenic benefit that is not attributable to a placebo effect from positive expectation and that was not explained by traditionally suggested mechanisms.
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Christian P. Cheung, Joshua T. Slysz and Jamie F. Burr
Antonio Dello Iacono, Stephanie Valentin, Mark Sanderson and Israel Halperin
Purpose: To investigate the test–retest reliability and criterion validity of the isometric horizontal push test (IHPT), a newly designed test that selectively measures the horizontal component of maximal isometric force. Methods: Twenty-four active males with ≥3 years of resistance training experience performed 2 testing sessions of the IHPT, separated by 3 to 4 days of rest. In each session, subjects performed 3 maximal trials of the IHPT with 3 minutes of rest between them. The peak force outputs were collected simultaneously using a strain gauge and the criterion equipment consisting of a floor-embedded force plate. Results: The test–retest reliability of peak force values was nearly perfect (intraclass correlation coefficient = ∼.99). Bland–Altman analysis showed excellent agreement between days with nearly no bias for strain gauge 1.2 N (95% confidence interval [CI], −3 to 6 N) and force plate 0.8 N (95% CI, −4 to 6 N). A nearly perfect correlation was observed between the strain gauge and force plate (r = .98, P < .001), with a small bias of 8 N (95% CI, 1.2 to 15 N) in favor of the force plate. The sensitivity of the IHPT was also good, with smallest worthwhile change greater than standard error of measurement for both the strain gauge (smallest worthwhile change: 29 N; standard error of measurement: 17 N; 95% CI, 14 to 20 N) and the force plate (smallest worthwhile change: 29 N; standard error of measurement: 18 N; 95% CI, 14 to 19 N) devices. Conclusions: The high degree of validity, reliability, and sensitivity of the IHPT, coupled with its affordability, portability, ease of use, and time efficacy, point to the potential of the test for assessment and monitoring purposes.
Borja Muniz-Pardos, Alejandro Gómez-Bruton, Ángel Matute-Llorente, Alex González-Agüero, Alba Gómez-Cabello, José A. Casajús and Germán Vicente-Rodríguez
Purpose: To examine the effects of a 6-month whole-body vibration (WBV) training on lower-body strength (LBS), lower-body power (LBP), and swimming performance in adolescent trained swimmers. Methods: Thirty-seven swimmers (23 males and 14 females; 14.8 [1.3] y) were randomly assigned to the WBV (n = 20) or the control group (n = 17). Isometric LBS (knee extension and half squat) and LBP (vertical and horizontal jumps and 30-m sprint) tests were performed before and after the intervention period. Swimming performance times in 100 m were collected from official competitions. As time × sex interaction was not found for any variable (P > .05), males and females were analyzed as a whole. Results: Within-group analyses showed a most likely beneficial moderate effect of WBV on isometric knee extension (effect size [ES] = 0.63), 30-m sprint test (ES = 0.62), and 100-m performance (ES = 0.25), although these were corresponded with comparable small to moderate effects in the control group (ES = 0.73, 0.71, and 0.20, respectively). The control group obtained a small possibly beneficial effect of swimming-only training on vertical jump performance, whereas no effect was observed in the WBV group. Unclear effects were observed for the rest of the variables assessed. Between-group analyses revealed unclear effects of WBV training when compared with the control condition in all studied variables. Conclusions: There is no current evidence to support the use of WBV training, and therefore, coaches and sports specialists should select other methods of training when the aim is to increase LBS, LBP, or swimming performance.
Thomas Cattagni, Vincent Gremeaux and Romuald Lepers
Purpose: To examine the cardiorespiratory, muscular, and skeletal characteristics of an 83-year-old champion female master athlete (called DL in this study) who had set multiple world running records in the 80-to-84-year-old age group. Methods: Measures of maximal oxygen uptake, maximal heart rate, maximal isometric torque for knee extensor muscles, thigh and triceps surae muscle volumes, and bone mineral density (BMD) of the proximal femur region were evaluated. Based on previously published equations, physiological age was determined for maximal oxygen uptake, maximal heart rate, and maximal isometric torque. Muscle volumes for the dominant leg were compared with previously published sex- and age-matched data using z scores. For BMD, T score and z score were calculated. Results: DL had the highest maximal oxygen uptake (42.3 mL·min−1·kg−1) ever observed for a female older than 80 years of age, which gave her a remarkable physiological age (27 y). By contrast, she had a physiological age closer to her biological age for maximal isometric torque (90 y) and maximal heart rate (74 y). The z scores for thigh (0.4) and triceps surae (1.1) muscle volumes revealed that DL’s leg muscles were affected almost as much as her sex- and age-matched peers. The T score (−1.7) for BMD showed that DL had osteopenia but no osteoporosis, and the z score (0.7) showed that DL’s BMD was similar to that of females of the same age. Conclusion: This single case study shows that the remarkable cardiorespiratory fitness coupled with intensive endurance training observed in a female master athlete was not associated with specific preservation of her muscular and skeletal characteristics.
Phillip Bellinger, Blayne Arnold and Clare Minahan
Purpose: To compare the training-intensity distribution (TID) across an 8-week training period in a group of highly trained middle-distance runners employing 3 different methods of training-intensity quantification. Methods: A total of 14 highly trained middle-distance runners performed an incremental treadmill test to exhaustion to determine the heart rate (HR) and running speed corresponding to the ventilatory thresholds (gas-exchange threshold and respiratory-compensation threshold), as well as fixed rating of perceived exertion (RPE) values, which were used to demarcate 3 training-intensity zones. During the following 8 weeks, the TID (total and percentage of time spent in each training zone) of all running training sessions (N = 695) was quantified using continuous running speed, HR monitoring, and RPE. Results: Compared with the running-speed-derived TID (zone 1, 79.9% [7.3%]; zone 2, 5.3% [4.9%]; and zone 3, 14.7% [7.3%]), HR-demarcated TID (zone 1, 79.6% [7.2%]; zone 2, 17.0% [6.3%]; and zone 3, 3.4% [2.0%]) resulted in a substantially higher training time in zone 2 (effect size ± 95% confidence interval: −1.64 ± 0.53; P < .001) and lower training time in zone 3 (−1.59 ± 0.51; P < .001). RPE-derived TID (zone 1, 39.6% [8.4%]; zone 2, 31.9% [8.7%]; and zone 3, 28.5% [11.6%]) reduced time in zone 1 compared with both HR (−5.64 ± 1.40; P < .001) and running speed (−5.69 ± 1.9; P < .001), whereas time in RPE training zones 2 and 3 was substantially higher than both HR- and running-speed-derived zones. Conclusion: The results show that the method of training-intensity quantification substantially affects computation of TID.
Taylor K. Dinyer, M. Travis Byrd, Ashley N. Vesotsky, Pasquale J. Succi and Haley C. Bergstrom
Purpose: To determine if the mathematical model used to derive critical power could be used to identify the critical resistance (CR) for the deadlift; compare predicted and actual repetitions to failure at 50%, 60%, 70%, and 80% 1-repetition maximum (1RM); and compare the CR with the estimated sustainable resistance for 30 repetitions (ESR30). Methods: Twelve subjects completed 1RM testing for the deadlift followed by 4 visits to determine the number of repetitions to failure at 50%, 60%, 70%, and 80% 1RM. The CR was calculated as the slope of the line of the total work completed (repetitions × weight [in kilograms] × distance [in meters]) vs the total distance (in meters) the barbell traveled. The actual and predicted repetitions to failure were determined from the CR model and compared using paired-samples t tests and simple linear regression. The ESR30 was determined from the power-curve analysis and compared with the CR using paired-samples t tests and simple linear regression. Results: The weight and repetitions completed at CR were 56 (11) kg and 49 (14) repetitions. The actual repetitions to failure were less than predicted at 50% 1RM (P < .001) and 80% 1RM (P < .001) and greater at 60% 1RM (P = .004), but there was no difference at 70% 1RM (P = .084). The ESR30 (75  kg) was greater (P < .001) than the CR. Conclusions: The total work-vs-distance relationship can be used to identify the CR for the deadlift, which reflected a sustainable resistance that may be useful in the design of resistance-based exercise programs.
Xiaolin Yang, Irinja Lounassalo, Anna Kankaanpää, Mirja Hirvensalo, Suvi P. Rovio, Asko Tolvanen, Stuart J.H. Biddle, Harri Helajärvi, Sanna H. Palomäki, Kasper Salin, Nina Hutri-Kähönen, Olli T. Raitakari and Tuija H. Tammelin
Background: The purpose of this study was to examine trajectories of leisure-time physical activity (LTPA) and television-viewing (TV) time and their associations in adults over 10 years. Methods: The sample comprised 2934 participants (men, 46.0%) aged 24–39 years in 2001 and they were followed up for 10 years. LTPA and TV time were assessed using self-report questionnaires in 2001, 2007, and 2011. Longitudinal LTPA and TV-time trajectories and their interactions were analyzed with mixture modeling. Results: Three LTPA (persistently highly active, 15.8%; persistently moderately active, 60.8%; and persistently low active, 23.5%) and 4 TV time (consistently low, 38.6%; consistently moderate, 48.2%; consistently high, 11.7%; and consistently very high, 1.5%) trajectory classes were identified. Persistently highly active women had a lower probability of consistently high TV time than persistently low-active women (P = .02), whereas men who were persistently highly active had a higher probability of consistently moderate TV time and a lower probability of consistently low TV time than their persistently low-active counterparts (P = .03 and P = .01, respectively). Conclusions: Maintaining high LTPA levels were accompanied by less TV over time in women, but not in men. The associations were partially explained by education, body mass index, and smoking.
David Morawetz, Tobias Dünnwald, Martin Faulhaber, Hannes Gatterer, Lukas Höllrigl, Christian Raschner and Wolfgang Schobersberger
Background: The altering effects of hypoxia on aerobic/anaerobic performance are well documented and form the basis of this study. Application of hyperoxic gases (inspiratory fraction of oxygen [FiO2] > 0.2095) prior to competition or training (hyperoxic preconditioning) can compensate for the negative influence of acute hypoxia. Purpose: To investigate whether oxygen supplementation immediately prior to exercise (FiO2 = 1.0) improves all-out exercise performance in normobaric hypoxia (3500 m) in highly skilled skiers. Methods: In this single-blind, randomized, crossover study, 17 subjects performed a 60-second constant-load, all-out test in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 minutes prior to the all-out test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times, and muscle oxygenation was assessed with near-infrared spectroscopy. Results: Absolute and relative peak power (P = .073 vs P = .103) as well as mean power (P = .330 vs P = .569) did not significantly differ after the hyperoxic preconditioning phase. PaO2 increased from 51.3 (3) to 451.9 (89.0) mm Hg, and SaO2 increased from 88.2% (1.7%) to 100% (0.2%) and dropped to 83.8% (4.2%) after the all-out test. Deoxygenation (P = .700) and reoxygenation rates (P = .185) did not significantly differ for both preconditioned settings. Conclusions: Therefore, the authors conclude that hyperoxic preconditioning did not enhance 60-second all-out exercise performance in acute hypoxia (3500 m).
Petros G. Botonis, Ioannis Malliaros, Gavriil G. Arsoniadis, Theodoros I. Platanou and Argyris G. Toubekis
Purpose: To examine the acute physiological responses and internal training load of long-interval swimming and water polo–specific drills in high-level water polo players. Methods: A total of 10 water polo players performed both a high-intensity swimming without ball (SW) with intensity corresponding to 90% of their maximum speed previously attained during a 300-m swimming test or a counterattack ball drill (CA). Both SW and CA conditions were designed to provide equal time exposure. Thus, 3 bouts of 4 minutes duration and a 3-minute passive rest were performed in each condition. The players’ physiological responses were assessed by continuous monitoring heart rate (HR) during CA and SW as well as by measuring blood lactate at the end of each condition. Rating of perceived exertion was recorded at the end of each bout. The Edwards summated HR zones were used to measure internal training load. Results: Both peak and mean HR were similar between SW and CA, and no difference was detected between conditions in the percentage time spent at 90% to 100% of HRpeak. Postexercise blood lactate (8.5 [4.1] vs 11.5 [1.9] mmol·L−1) and rating of perceived exertion (8.1 [0.8] vs 8.7 [0.5] a.u.) values were lower in CA compared with SW (P < .05). Conclusions: SW compared with CA showed similar cardiac stress but increased anaerobic metabolism activation and higher rating of perceived exertion. Either CA or SW may be both used in training practice as a means to effectively train physical conditioning of water polo players, whereas CA may also facilitate tactical preparation.
Jordan L. Fox, Robert Stanton, Charli Sargent, Cody J. O’Grady and Aaron T. Scanlan
Purpose: To quantify and compare external and internal game workloads according to contextual factors (game outcome, game location, and score-line). Methods: Starting semiprofessional, male basketball players were monitored during 19 games. External (PlayerLoad™ and inertial movement analysis variables) and internal (summated-heart-rate-zones and rating of perceived exertion [RPE]) workload variables were collected for all games. Linear mixed-effect models and effect sizes were used to compare workload variables based on each of the contextual variables assessed. Results: The number of jumps, absolute and relative (in min−1) high-intensity accelerations and decelerations, and relative changes-of-direction were higher during losses, whereas session RPE was higher during wins. PlayerLoad™ the number of absolute and relative jumps, high-intensity accelerations, absolute and relative total decelerations, total changes-of-direction, summated-heart-rate-zones, session RPE, and RPE were higher during away games, whereas the number of relative high-intensity jumps was higher during home games. PlayerLoad™, the number of high-intensity accelerations, total accelerations, absolute and relative decelerations, absolute and relative changes-of-direction, summated-heart-rate-zones, sRPE, and RPE were higher during balanced games, whereas the relative number of total and high-intensity jumps were higher during unbalanced games. Conclusions: Due to increased intensity, starting players may need additional recovery following losses. Given the increased external and internal workload volumes encountered during away games and balanced games, practitioners should closely monitor playing times during games. Monitoring playing times may help identify when players require additional recovery or reduced training volumes to avoid maladaptive responses across the in-season.