Running Time Trial Research Articles

Aerobic Exercise Performance During Load Carriage and Acute Altitude Exposure.

Coffman, KE, Luippold, AJ, Salgado, RM, Heavens, KR, Caruso, EM, Fulco, CS, and Kenefick, RW. Aerobic exercise performance during load carriage and acute altitude exposure. J Strength Cond Res 34(4): 946-951, 2020-This study quantified the impact of combined load carriage and acute altitude exposure on 5-km running time-trial (TT) performance and self-selected pacing strategy. Furthermore, this study developed a velocity prediction tool (nomogram) for similar aerobic exercise tasks performed under various combinations of altitude and load stress. Nine volunteers (6M/3F, age: 24 ± 7 years, height: 171 ± 6 cm, body mass: 72 ± 7 kg, and V[Combining Dot Above]O2peak: 50.5 ± 5.2 ml·min·kg) completed a randomized, repeated-measures design protocol. Volunteers performed 3 familiarization (FAM) trials at sea level (SL; 250 m) with no-load carriage. Experimental testing included 3 self-paced, blinded 5-km running TT on a treadmill while carrying a 30% body mass external load at SL, moderate altitude (MA; 2000 m), and high altitude (HA; 3000 m). At SL, load carriage resulted in a 36% decrement in 5-km exercise performance in comparison with FAM trials (43 ± 7 vs. 32 ± 3 minutes; p < 0.001). Time required to complete the 5-km distance while carrying an external load was increased by 11% when performed at HA vs. SL (48 ± 7 vs. 43 ± 7 minutes; p = 0.001). TT pace was not different among experimental conditions (load carriage at SL, MA, and HA) until after 1 km of the running distance had been completed. Heart rate was not different among experimental conditions throughout the entire TT (170 ± 17 b·min). These data quantify the anticipated reduction in aerobic exercise performance under various combinations of acute altitude exposure and load carriage conditions. The self-paced running TT approach used presently allowed for development of an altitude-load nomogram for use in recreational, occupational, or military settings.

Exercise in Thermal Inversions: PM2.5 Air Pollution Effects on Pulmonary Function and Aerobic Performance

Wintertime thermal inversions can lead to the accumulation of small particulate matter (PM2.5). Despite an association between respiratory hospital admissions and elevated PM2.5 levels, many people continue to exercise outdoors during inversions. This study compared pulmonary function and exercise performance during periods of low and high ambient PM2.5 concentrations. Forced vital capacity and forced expiratory volume in 1 s were measured outdoors before and after two 3200 m running time trials: one with low ambient PM2.5 (0.6-14.7 microgram·m-3), and the other during high PM2.5 (19.1-42.5 micrograms·m-3). A 10 cm visual analog scale (VAS) administered postexercise quantified subjective ratings of respiratory discomfort. The PM2.5 differential between trials was ≥18 micrograms·m-3 for 10 healthy runners. Despite feeling more respiratory discomfort (P=0.044) during the bad air trial (VAS: 4.6±1.8 cm) compared with the good air trial (VAS: 2.9±1.8 cm), the 3200 m run time (low PM2.5: 13:54±1:34 min:s; high PM2.5: 14:07±1:44 min:s) was not different (P=0.261) between trials. Postexercise forced vital capacity was not significantly different (P=0.846) between the low (4.86±1.00 L) and high (4.84±0.95 L) PM2.5 conditions. Similarly, the difference in postexercise forced expiratory volume in 1 s was not significant (P=0.750) between trials (4.22±0.89 L vs 4.23±0.85 L). Neither run time nor pulmonary function of healthy adults were adversely affected by an acute bout of exercise in elevated ambient PM2.5, equivalent to yellow or orange on the air quality index.

Effect of neuromuscular resistance training on the performance of 5-km runners

The study aimed to identify the effect of a neuromuscular resistance training protocol (NRTP) on the performance of 5-km distance runners. This study included 18 male runners (age=29.3±3.2 years, fat percentage=11.3±2.6%, body height=1.77±.04 m, body mass=73.4±4.4 kg, time in 5 km=20.6±2.4 min, training years=4.3±0.7 years). First, volunteers were anthropometrically evaluated, and they performed one-repetition maximum (1RM) 45º leg press (LP) strength test. Second, they performed an incremental protocol in the 45º LP to acquire the electromyographic threshold. Third, they completed a 5-km time trial run (5 km basal). In the fourth session, they performed NRTP in LP. And fifth, the 5-km time trial run was performed at 30 min, 48 h, 96 h, and 144 h post the NRTP intervention. A significant decrease (p≤.05) was observed when baseline values were compared with post 30 min and post 48 h (p=.02 and p=.04, respectively). However, there were significant positive differences in performance (p=.04 for time) when baseline values and post 144 h were analyzed. Therefore, it is concluded that the NRTP can be used by 5-km distance runners to improve their performance with a break of one week between the intervention and test.

Does fatigue alter step characteristics and stiffness during running?

BackgroundDescribing the response of spatiotemporal gait characteristics, and related variables such as variability and stiffness, to different stressors is important to better understand spring-mass model. Research questionThis study aimed to examine the effect of fatigue induced by a running protocol on spatiotemporal gait parameters, step variability and vertical (Kvert) and leg stiffness (Kleg) during running on a treadmill. MethodsTwenty-two trained male endurance runners performed a 60-min time trial run. An analysis of spatiotemporal parameters (contact time [CT], flight time [FT], step frequency [SF] and step length [SL]), step variability (in terms of coefficient of variation [CV]) and stiffness was conducted in two different conditions: non-fatigued (before the protocol) and fatigued (after the protocol). ResultsThe pairwise comparisons (i.e., non-fatigued vs. fatigued condition) indicated that temporal parameters (i.e., CT and FT) experienced significant changes (p = 0.001 and <0.001, respectively). Step variability increased in presence of fatigue, with higher CV in CT (p = 0.039), FT (p = 0.005), SF (p = 0.046) and SL (p = 0.027) after the running protocol. The Kleg experienced a reduction in the fatigued condition (p < 0.001) whereas the Kvert remained unchanged (p = 0.602). SignificanceThe results indicate that fatigue induced by a 60-min time trial run causes some adaptations in spatiotemporal gait characteristics and stiffness in trained endurance runners. Specifically, in the presence of fatigue, the athletes showed greater CT and shorter FT, higher step variability and lower leg stiffness.

Influence of Altitude and Environmental Temperature on Muscle Functional and Mechanical Activation After 30' Time Trial Run

The purpose of this study was to explore the influence of altitude and environmental temperature on muscle mechanical and functional activation after 30' Time Trial run (30' TT). Twenty physical active males (Age= 20.4 ±3.21 years, VO2max= 47.2 ±5.2 ml/kg/min) performed a 30' TT in three different conditions of altitude and temperature: Control Condition [CC] (1137 m.a.s.l. at 26 ±1.5°C), Heat-Low Condition [HLC] (3 m.a.s.l. at 30.5 ±0.6°C), and Cool-High Condition [CHC] (2369 m.a.s.l. at 14.2 ±0.6°C). Tensiomyography (TMG), Countermovement Jump (CMJ), and Delayed Onset Muscle Soreness (DOMS) were measured pre and post running. During the 30' TT, distance, speed, heart rate (HR), rate of perceived exertion (RPE), and thermal index (WBGT) were measured. Results show a significant decrease in body weight and a significant increase in DOMS and jump height in CMJ after running in each condition. TMG responses increased maximum radial muscle displacement (Dm) and decreased muscle contraction time (Tc) both rectus and biceps femoris muscles after running. During the 30' TT, the results did not show a significant difference in RPE, HR, distance, and speed among conditions. In conclusion, altitude and temperature seem not to significantly affect the mechanical and functional responses 30' TT, despite the tendency of HLC to decrease both activation and performance.

Accelerometer detected lateral sway during a submaximal running test correlates with endurance exercise performance in elite Australian male cricket players

ObjectiveTo identify whether movement patterns during a standardized submaximal running test (SSRT), assessed by accelerometry, were associated with improvements in endurance exercise performance. DesignA retrospective analysis of data collected from the 2018–2019 Australian cricket preseason. MethodsThirty-nine high-performance male cricket players were studied (25±3 years, 82±6kg, 183±6cm). SSRT was performed monthly prior to a two kilometre (km) running time trial (2kmTT). SSRT involved running between markers, positioned twenty metres apart, for three minutes. Foot strikes were timed to a metronome (154beats/min) to elicit a running speed of ˜eight km/h. Triaxial accelerometers were worn in vests on the upper back and used to assess PlayerLoad medio-lateral vector (PL1Dside%), vertical vector (PL1Dup%) and anterior-posterior vector (PL1Dfwd%) were assessed. Results2kmTT performance improved over the study period (p<0.05). PlayerLoad vectors during the first minute of SSRT were not related to 2kmTT performance (p>0.23). During the second and third minutes there were positive associations between 2kmTT (run time) and PL1Dside% (SSRT2min, β 2.12, p<0.03, 95% CI: 0.22–4.01; SSRT3min, β 2.30, p<0.03, 95% CI:0.32–4.29), but not PL1Dup% (SSRT2min, β −0.15, p=0.77, 95% CI: −1.13–0.83; SSRT3min, β −0.15, p=0.77, 95% CI: −1.11–0.87) or PL1Dfwd% (SSRT2min, β −0.45, p=0.42, 95% CI: −1.49–0.62; SSRT3min, B−0.45, p=0.40, 95% CI: −1.51–0.60). ConclusionAssessment of PL1Dside% during the second or third minutes of SSRT may inform how an athlete’s endurance exercise performance is responding to changes in training load.

Improved 1000-m Running Performance and Pacing Strategy With Caffeine and Placebo: A Balanced Placebo Design Study.

To investigate the placebo effect of caffeine on pacing strategy and performance over 1000-m running time trials using a balanced placebo design. Eleven well-trained male middle-distance athletes performed seven 1000-m time trials (1 familiarization, 2 baseline, and 4 experimental). Experimental trials consisted of the administration of 4 randomized treatments: informed caffeine/received caffeine, informed caffeine/received placebo, informed placebo/received caffeine, and informed placebo/received placebo. Split times were recorded at 200, 400, 600, 800, and 1000m, and peak heart rate and rating of perceived exertion were recorded at the completion of the trial. Relative to baseline, participants ran faster during informed caffeine/received caffeine (d = 0.42) and informed caffeine/received placebo (d = 0.43). These changes were associated with an increased pace during the first half of the trial. No differences were shown in pacing or performance between baseline and the informed placebo/received caffeine (d = 0.21) and informed placebo/received placebo (d = 0.10). No differences were reported between treatments for peak heart rate (η2 = .084) and rating of perceived exertion (η2 = .009). The results indicate that the effect of believing to have ingested caffeine improved performance to the same magnitude as actually receiving caffeine. These improvements were associated with an increase in pace during the first half of the time trial.

Effects of Maturation on Physical Fitness Adaptations to Plyometric Jump Training in Youth Females

Romero, C, Ramirez-Campillo, R, Alvarez, C, Moran, J, Slimani, M, Gonzalez, J, and Banzer, WE. Effects of maturation on physical fitness adaptations to plyometric jump training in youth females. J Strength Cond Res 35(10): 2870-2877, 2021-The aim of this study was to compare the effects of maturation on physical fitness adaptations to plyometric jump training (PJT) in youth females. Jumping, sprinting, change of direction speed, endurance, and maximal strength were measured pre-post 6 weeks of PJT in 7th- and 10th-grade subjects. In the seventh grade, subjects formed a PJT group (Plyo-7, n = 10; age, 12.7 ± 0.6 years; breast maturation stages IV [n = 2], III [n = 7], and II [n = 1]) and an active control group (Con-7, n = 9; age, 12.8 ± 0.6 years; breast maturation stages IV [n = 2], III [n = 6], and II [n = 1]). In the 10th grade, subjects conformed a PJT group (Plyo-10, n = 9; age, 16.3 ± 0.5 years; breast maturation stages V [n = 5] and IV [n = 4]) and an active control group (Con-10, n = 9; age, 16.2 ± 0.5 years; breast maturation stages V [n = 5] and IV [n = 4]). Magnitude-based inferences were used for data analysis, with effect sizes (ESs) interpreted as <0.2 = trivial; 0.2-0.6 = small; 0.6-1.2 = moderate; 1.2-2.0 = large; and 2.0-4.0 = very large. The Plyo-7 and Plyo-10 showed meaningful improvements in all physical fitness measures (ES = 0.21-2.22), while Con-7 and Con-10 showed only trivial changes. The Plyo-7 and Plyo-10 showed meaningful (ES = 0.16-2.22) greater improvements in all physical fitness measures when compared with their control counterparts. The Plyo-10 showed meaningful greater improvements in 20-m sprint, 2-km running time trial, maximal strength, squat jump, and drop jump from 20 cm (ES = 0.21-0.42) when compared with Plyo-7. In conclusion, PJT is effective in improving physical fitness in younger and older female youths. However, greater adaptations were observed in more mature subjects.

The Effects of Inhaled Terbutaline on 3-km Running Time-Trial Performance.

Terbutaline is a prohibited drug except for athletes with a therapeutic use exemption certificate; terbutaline's effects on endurance performance are relatively unknown. Purpose: To investigate the effects of 2 therapeutic (2 and 4mg) inhaled doses of terbutaline on 3-km running time-trial performance. Methods: A total of 8 men (age 24.3 [2.4]y; weight 77.6 [8]kg; and height 179.5 [4.3]cm) and 8 women (age 22.4 [3]y; weight 58.6 [6]kg; and height 163 [9.2]cm) free from respiratory disease and illness provided written informed consent. Participants completed 3-km running time trials on a nonmotorized treadmill on 3 separate occasions following placebo and 2- and 4-mg inhaled terbutaline in a single-blind, repeated-measures design. Urine samples (15min postexercise) were analyzed for terbutaline concentration. Data were analyzed using 1-way repeated-measures analysis of variance, and significance was set at P < .05 for all analyses. Results: No differences were observed for completion times (1103 [201]s, 1106 [195]s, 1098 [165]s; P = .913) for the placebo or 2- and 4-mg inhaled trials, respectively. Lactate values were higher (P = .02) after 4mg terbutaline (10.7 [2.3]mmol·L-1) vs placebo (8.9 [1.8]mmol·L-1). Values of forced expiratory volume in the first second of expiration (FEV1) were greater after inhalation of 2mg (5.08 [0.2]; P = .01) and 4mg terbutaline (5.07 [0.2]; P = .02) compared with placebo (4.83 [0.5]L) postinhalation. Urinary terbutaline concentrations were mean 306 (288) ng·mL-1 and 435 (410) ng·mL-1 (P = .2) and peak 956ng·mL-1 and 1244ng·mL-1 after 2 and 4mg inhaled terbutaline, respectively. No differences were observed between the male and female participants. Conclusions: Therapeutic dosing of terbutaline does not lead to an improvement in 3-km running performance despite significantly increased FEV1. The findings suggest that athletes using inhaled terbutaline at high therapeutic doses to treat asthma will not gain an ergogenic advantage during 3-km running performance.

No Benefit of Ingestion of a Ketone Monoester Supplement on 10-km Running Performance.

Preexercise ingestion of exogenous ketones alters the metabolic response to exercise, but effects on exercise performance have been equivocal. On two occasions in a double-blind, randomized crossover design, eight endurance-trained runners performed 1 h of submaximal exercise at approximately 65% V˙O2max immediately followed by a 10-km self-paced time trial (TT) on a motorized treadmill. An 8% carbohydrate-electrolyte solution was consumed before and during exercise, either alone (CHO + PLA), or with 573 mg·kg of a ketone monoester supplement (CHO + KME). Expired air, HR, and RPE were monitored during submaximal exercise. Serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate concentrations. CHO + KME produced plasma β-hydroxybutyrate concentrations of approximately 1.0 to 1.3 mM during exercise (P < 0.001), but plasma glucose and lactate concentrations were similar during exercise in both trials. V˙O2, running economy, respiratory exchange ratio, HR, and RPE were also similar between trials. Performance in the 10-km TT was not different (P = 0.483) between CHO + KME (mean, 2402 s; 95% confidence interval, 2204-2600 s) and CHO + PLA (mean, 2422 s; 95% confidence interval, 2217-2628 s). Cognitive performance, measured by reaction time and a multitasking test, did not differ between trials. Compared with carbohydrate alone, coingestion of KME by endurance-trained athletes elevated plasma β-hydroxybutyrate concentrations, but did not improve 10-km running TT or cognitive performance.

Acute Capsaicin Supplementation Improves 400 and 3000 Meters Running Time-trial Performance in a Distance-dependent Way

Ergogenic effect of capsaicin has been shown in middle-distance time trial (1500 meters) but not in repeated maximal sprints indicating the need of explore exercises with different metabolic demands. PURPOSE: The purpose of this study was to investigate the acute effect of capsaicin supplementation on short (400 m) and middle distance (3000 m) running time-trial performance, maximum heart rate and rate of perceived exertion in physically active adults. METHODS: Twelve physically active men (age= 28.6±5.4 y) completed four randomized, double-blind trials: Capsaicin condition (12 mg) or a placebo condition. Forty-five minutes after supplement consumption, the participants performed a randomized 400- or 3000-meters running time trial. Time (in seconds) was recorded. Heart rate was analyzed at rest and immediately post-exercise, and the rate of perceived exertion (RPE) was collected immediately after exercise. The effect of capsaicin on time-trial performance, maximum heart rate and rate of perceived exertion during short (400 m) and middle distance (3000 m) running were analyzed via a Paired t test. In addition, the effect size (ES, 90% confidence interval [CI]) and magnitude-based inference statistics in the selected variables were calculated. RESULTS: For 400 m time-trial (Capsaicin= 66.4 + 4.2 sec vs Placebo= 67.1 + 4.8 sec, t= 2.250, p= 0.046) and 3000 m time-trial (Capsaicin= 876.2 + 76.1 sec vs Placebo= 905.1 + 73.3 sec, t= 2.848, p= 0.016) the time in seconds was significantly lesser in the capsaicin compared to placebo. Capsaicin showed a likely small improvement of performance in the 3000 m (d= 0.40, IC 90%= -0.60 to -0.14) and likely trivial in the 400 m (d= 0.13, IC 90%= -0.24 to -0.03). There was no statistically significant difference for the maximum heart rate (400m: p=0.114; 3000m: p= 0.319) and RPE (400m: p=0.615; 3000m: p= 0.438). CONCLUSION: In summary, acute capsaicin supplementation improved 400 m and 3000 m running time-trial performance in a distance-dependent way without modifying RPE and maximum heart rate in physically active adults. Furthermore, the present study showed a meaningful improvement in the performance during 3000 m running time-trial.

Biomechanical Adaptations and Performance Indicators in Short Trail Running.

Our aims were to measure anthropometric and oxygen uptake (O2) variables in the laboratory, to measure kinetic and stride characteristics during a trail running time trial, and then analyse the data for correlations with trail running performance. Runners (13 men, 4 women: mean age: 29 ± 5 years; stature: 179.5 ± 0.8 cm; body mass: 69.1 ± 7.4 kg) performed laboratory tests to determine O2 max, running economy (RE), and anthropometric characteristics. On a separate day they performed an outdoor trail running time trial (two 3.5 km laps, total climb: 486 m) while we collected kinetic and time data. Comparing lap 2 with lap 1 (19:40 ± 1:57 min vs. 21:08 ± 2:09 min, P < 0.001), runners lost most time on the uphill sections and least on technical downhills (-2.5 ± 9.1 s). Inter-individual performance varied most for the downhills (CV > 25%) and least on flat terrain (CV < 10%). Overall stride cycle and ground contact time (GCT) were shorter in downhill than uphill sections (0.64 ± 0.03 vs. 0.84 ± 0.09 s; 0.26 ± 0.03 vs. 0.46 ± 0.90 s, both P < 0.001). Force impulse was greatest on uphill (248 ± 46 vs. 175 ± 24 Ns, P < 0.001) and related to GCT (r = 0.904, P < 0.001). Peak force was greater during downhill than during uphill running (1106 ± 135 vs. 959 ± 104 N, P < 0.01). Performance was related to absolute and relative O2 max (P < 0.01), vertical uphill treadmill speed (P < 0.001) and fat percent (P < 0.01). Running uphill involved the greatest impulse per step due to longer GCT while downhill running generated the highest peak forces. O2 max, vertical running speed and fat percent are important predictors for trail running performance. Performance between runners varied the most on downhills throughout the course, while pacing resembled a reversed J pattern. Future studies should focus on longer competition distances to verify these findings and with application of measures of 3D kinematics.

Anticipated Task Difficulty Provokes Pace Conservation and Slower Running Performance.

Models of self-paced endurance performance suggest that accurate knowledge of the exercise end-point influences pace-related decision making. No studies have examined the effects of anticipated task difficulty during equidistant endurance activities. Accordingly, the purpose of this study was to investigate the effects of anticipated task difficulty on pacing, psychological, and physiological responses during running time trials. Twenty-eight trained runners completed three self-paced 3000-m time trials. The first was a baseline time trial completed on a 0% treadmill gradient. Time trials 2 and 3 were counterbalanced. Before a known incline time trial, anticipated to be more difficult, subjects were accurately informed that the gradient would increase to 7% for the final 800 m. Before an equivalent, unknown incline (UI) time trial subjects were deceptively informed that the gradient would remain at 0% throughout. Expressed relative to baseline, running speed was 2.44% slower (d = -0.47) over the first 2200 m during known incline (KI) time trial than UI time trial. Effort perception, affective valence, heart rate, and blood lactate did not differ between time trials. Initial running speed during KI was related to pretrial motivation, pretrial vigor, perceived effort, and affective valence (all r ≥ 0.382). No such relationships existed during UI. More subjects also reported a conscious focus on pacing during KI. An anticipated increase in task difficulty provoked pace conservation during 3000 m running time trials. The reduced pace may have resulted from greater task uncertainty and consciously aware, effort- and affect-based decisions to conserve energy and maintain hedonic state during KI. The findings add to theoretical understandings of factors that influence pacing during endurance activity. Consequently, recommendations to minimize the potentially deleterious effects of anticipated increases in task difficulty are provided.

Photoplethysmography Detection of Overreaching.

Detecting the onset of functional overreaching (FOR) or nonfunctional overreaching in endurance athletes is of prior importance to ensure reactive amendment of the scheduled training program. The objective of this study was to assess photoplethysmography (PPG) in overloaded athletes and test whether 1) it would be affected differently in functional overreached (FOR) or nonoverreached acutely fatigued (AF) athletes and 2) specific PPG characteristics would allow for timely distinction of FOR and AF. Fifteen athletes performed 2-wk baseline training followed by 3-wk overload (+45%; OVL) and 2-wk recovery (-20%). Three-thousand-meter time-trial running was used to assess performance at the end of baseline, OVL, and recovery and distinguish FOR and AF. PPG was recorded overnight using a wearable sensor, every third night. Overnight means and variances of systolic, diastolic, and dicrotic amplitudes and times as well as systolic and diastolic slopes were used to discriminate FOR and AF athletes. Performance was decreased in FOR and improved in AF at the end of OVL. Diastolic time was greater in AF than FOR, whereas systolic slope was smaller in AF than in FOR during OVL. The variances of systolic, diastolic, dicrotic amplitudes, systolic, diastolic slopes, and pulse areas were smaller in AF compared with FOR in the last week of OVL. PPG is an efficient tool for the detection of overreaching because it distinguished FOR and AF athletes during OVL (prior performance decrement). This fast-responding method would therefore allow for adjusting the daily training content to prevent nonfunctional overreaching.

Two-Day Residence at 2500 m to 4300 m Does Not Affect Subsequent Exercise Performance at 4300 m.

To determine the efficacy residing for 2 d at various altitudes while sedentary (S) or active (A; ~90 min hiking 2 d) on exercise performance at 4300 m. Sea-level (SL) resident men (n = 45) and women (n = 21) (mean ± SD; 23 ± 5 yr; 173 ± 9 cm; 73 ± 12 kg; V˙O2peak = 49 ± 7 mL·kg·min) were randomly assigned to a residence group and, S or A within each group: 2500 m (n = 11S, 8A), 3000 m (n = 6S, 12A), 3500 m (n = 6S, 8A), or 4300 m (n = 7S, 8A). Exercise assessments occurred at SL and 4300 m after 2-d residence and consisted of 20 min of steady-state (SS) treadmill walking (45% ± 3% SL V˙O2peak) and a 5-mile, self-paced running time trial (TT). Arterial oxygen saturation (SpO2) and HR were recorded throughout exercise. Resting SpO2 was recorded at SL, at 4 and 46 h of residence, and at 4300 m before exercise assessment. To determine if 2-d altitude residence improved 4300 m TT performance, results were compared with estimated performances using a validated prediction model. For all groups, resting SpO2 was reduced (P < 0.01) after 4 h of residence relative to SL inversely to the elevation and did not improve after 46 h. Resting SpO2 (~83%) did not differ among groups at 4300 m. Although SL and 4300 m SS exercise SpO2 (97% ± 2% to 74% ± 4%), HR (123 ± 10 bpm to 140 ± 12 bpm) and TT duration (51 ± 9 to 73 ± 16 min) were different (P < 0.01), responses at 4300 m were similar among all groups, as was actual and predicted 4300 m TT performances (74 ± 12 min). Residing for 2 d at 2500 to 4300 m, with or without daily activity, did not improve resting SpO2, SS exercise responses, or TT performance at 4300 m.

Critical Velocity during Intermittent Running with Changes of Direction.

We tested the hypothesis that critical velocity (CV) during intermittent running with changes of direction is reliably and accurately identified from a simple shuttle field test. We also tested the hypothesis that CV during intermittent running with changes of direction running is not equivalent to continuous linear running. Young adults performed a custom shuttle test of intermittent sprint running to reveal CV. Sprints were 18.3 m per direction, with rest between sprints of 15 s for 3 min, 10 s for 2 min, and no rest for 2 min (7 min total). To test reliability, the CV shuttle test (CVST) was performed twice. To test validity, blood lactate was assessed during two separate trials inclusive of 5% above or below CVST end velocity. To explore task specificity, CV during CVST was compared to CV obtained from three linear running time trials. Total distance and CSVT end test velocity were similar between visits (864 ± 21 m and 3.23 ± 0.13 m·s vs 900 ± 30 m and 3.21 ± 0.15 m·s, respectively). At 5% above CVST end velocity, all subjects failed to complete 20 min and had unstable blood lactate values. A steady state blood lactate profile was observed during trials 5% below end velocity and all subjects completed the trial. The CV from the CVST was lower than the CV from linear running (△ -17% ± 6%), highlighting the importance of test specificity for threshold determination. The CVST provides a reliable and accurate determination of CV and can be used by coaches, athletes, and trainers to better understand the physiological impact specific to practice or competitions involving intermittent change of direction running.

Cold-water immersion combined with active recovery is equally as effective as active recovery during 10 weeks of high-intensity combined strength and endurance training in men

Summary Study aim: The purpose of this study was to compare the effects of cold-water immersion (CWI) vs. active recovery performed after each individual strength and endurance training session over a 10-week period of high-intensity combined strength and endurance training. Materials and methods: Seventeen healthy men completed 10 weeks of high-intensity combined strength and endurance training. One group (AR, n = 10) completed active recovery that included 15 minutes of running at 30–40% VO2max after every strength training session while the other group (CWI, n = 7) completed 5 minutes of active recovery (at the same intensity as the AR group) followed by 10 minutes of cold-water (12 ± 1°C) immersion. During CWI, the subjects were seated passively during the 10 minutes of cold-water immersion and the water level remained just below the pectoral muscles. Muscle strength and power were measured by isometric bilateral, 1 repetition maximum, leg press (ISOM LP) and countermovement jump (CMJ) height. Endurance performance was measured by a 3000 m running time trial. Serum testosterone, cortisol, and IGF-1 were assessed from venous blood samples. Results: ISOM LP and CMJ increased significantly over the training period, but 3000 m running time increased only marginally. Serum testosterone, cortisol, and IGF-1 remained unchanged over the intervention period. No differences between the groups were observed. Conclusions: AR and CWI were equally effective during 10 weeks of high-intensity combined strength and endurance training. Thus, physically active individuals participating in high-intensity combined strength and endurance training should use the recovery method they prefer.

Beta-Alanine Supplementation Improved 10-km Running Time Trial in Physically Active Adults.

The purpose of this study was to investigate the effects of β-alanine supplementation on a 10 km running time trial and lactate concentration in physically active adults. Sixteen healthy subjects were divided randomly into two groups: β-alanine (n = 8) and placebo group (n = 8). The experimental group ingested 5 g/day of β-alanine plus 1 g of resistant starch, and control group ingested 6 g of resistant starch, both for 23 days. Time to complete a 10-km running time trial and lactate concentration following the test were assessed at baseline and post 23 days. The running training program was performed three times per week on non-consecutive days (day 1: running 7 km; day 2: six sprints of 500 m at maximum speed with 2 min of recovery; day 3: running 12 km). The time to complete a 10-km running time trial decreased significantly only for the β-alanine group (Pre = 3441 ± 326.7, Post = 3209 ± 270.5 s, p < 0.05). When analyzing the delta (Time post minus Time at baseline value) there was a statistically significant difference between the β-alanine vs placebo group (-168.8 ± 156.6 vs. -53.60 ± 78.81 s, p = 0.007), respectively. In addition, the β-alanine group presented lower blood lactate concentration after the 10-km test (β-alanine: Pre = 8.45 ± 1.94 vs. Post = 6.95 ± 2.44 mmol/L; Placebo: Pre = 8.7 ± 3.0 vs. Post = 10.8 ± 2.5 mmol/L, p = 0.03). In conclusion, β-alanine supplementation improved the 10-km running time trial and reduced lactate concentration in physically active adults.

Wearing compression socks during exercise aids subsequent performance

ObjectivesTo assess the effect of wearing compression socks on immediate and subsequent 5km running time trials, with particular attention to the influences on physiological, perceptual and performance-based parameters. DesignCounter-balanced cross-over experiment. MethodsTwelve male runners (mean±SD 5km run time 19:29±1:18min:s) each completed two experimental sessions. Sessions consisted of a standardised running warm-up, followed by a 5km time trial (TT1), a one hour recovery period, then a repeat of the warm-up and 5km time trial (TT2). One session required the use of sports compression socks during the first warm-up and time trial (COMP), while the other did not (CON). ResultsThe decline in run performance in CON from TT1 to TT2 was moderate and significantly greater than that experienced by runners in COMP (9.6s, d=0.67, p<0.01). No difference was found between experimental conditions for oxygen consumption, blood lactate or calf volume (p=0.61, 0.54, 0.64, respectively). Perceptual measures of muscle soreness, fatigue and recovery were also similar between trials (p=0.56, 1.00 & 0.61, respectively). ConclusionsWearing sports compression socks during high intensity running has a positive impact on subsequent running performance. The underlying mechanism of such performance enhancement remains unclear, but may relate to improved oxygen delivery, reduced muscle oscillation, superior running mechanics and athlete beliefs.

The Impact of a Novel Wrist Cooling Device on 10km Running Performance in the Heat

The combination of environmental heat stress and exercise is a potent physiological challenge and is known to impair performance. While pre-cooling might improve performance in the heat, it may prove impractical. PURPOSE: to investigate the impact of a novel wrist cooling device (DhamaSportTM), which can be worn during exercise, on exercise performance and physiological responses in the heat. METHODS: In a single-blind, counterbalanced, crossover design, 13 male athletes (33±9 yrs, 15±7 %body fat, and VO max 59 ± 5 ml/kg/min, range 50-71) completed three 10km running time trials in the heat (80°F, 60% relative humidity), while wearing two DhamaSportTM bands: 1) both bands were off (off/off), 2) one band on (off/on), 3) both bands on (on/on). Heart rate (HR), core temperature (TCO), running speed (RS), rating of perceived exertion (RPE) and thermal sensations (TS) were recorded at baseline, during the 10km TT, and during recovery. To understand potential impacts on recovery and fatigue post-exercise, heart rate variability (root mean square of successive differences; RMSSD, and standard deviation of N-N intervals; SDNN), mean arterial pressure (MAP), and visual analog scale (VAS) for fatigue were measured. Due to safety constraints, trials were terminated if TCO >39.2°C, in which average speed was used to estimate 10km time. RESULTS: Use of the cooling bands had no effect (p<0.05) on resting TCO, MAP, TS, VAS, RPE, RMSSD, or SDNN, but modestly increased (p>0.05) HR ([INCREMENT]3-5 beats/min). During exercise, use of the bands significantly (p<0.05) increased RS (-0.25 [INCREMENT]mi/hr), HR (5 [INCREMENT]beats/min), but had no significant effects on TCO ([INCREMENT]0.3°C), RPE, or TS were observed over time. The increased RS with the use of the bands, tended to reduce projected 10km time (~10-30s). Use of the cooling bands did not impact RMSSD, SDNN, MAP, or fatigue post- exercise (p>0.05). CONCLUSION: Our data demonstrate that use of the cooling bands improves running speed, decreasing projected 10km time. This modest improvement in performance comes at a cost of increased HR; although, interestingly, sensations of effort and thermal comfort were not impacted, despite the faster speed and higher HR. Taken together, use of the cooling bands has the potential to improve exercise performance in the heat perhaps due to altered thermal sensation. Support: Dhamausa.