This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on postexercise acid-base balance recovery kinetics and subsequent high-intensity cycling time to exhaustion. In a counterbalanced, crossover design, nine healthy and active males (age: 23 ± 2 years, height: 179 ± 5 cm, body mass: 74 ± 9 kg, peak mean minute power (Wpeak) 256 ± 45 W, peak oxygen uptake (V̇O2peak) 46 ± 8 ml.kg-1.min-1) performed a graded incremental exercise test, two familiarization and two experimental trials. Experimental trials consisted of cycling to volitional exhaustion (TLIM1) at 100% WPEAK on two occasions (TLIM1 and TLIM2) interspersed by a 90 min passive recovery period. Using a double-blind approach, 30 min into a 90 min recovery period participants ingested either 0.3 g.kg-1 body mass sodium bicarbonate (NaHCO3) or a placebo (PLA) containing 0.1 g.kg-1 body mass sodium chloride (NaCl) mixed with 4 ml.kg-1 tap water and 1 ml.kg-1 orange squash. The mean differences between TLIM2 and TLIM1 was larger for PLA compared with NaHCO3 (-53 ± 53 vs. -20 ± 48 s; p = .008, d = 0.7, CI =-0.3, 1.6), indicating superior subsequent exercise time to exhaustion following NaHCO3. Blood lactate [Bla-] was similar between treatments post TLIM1, but greater for NaHCO3 post TLIM2 and 5 min post TLIM2. Ingestion of NaHCO3 induced marked increases (p < .01) in both blood pH (+0.07 ± 0.02, d = 2.6, CI = 1.2, 3.7) and bicarbonate ion concentration [HCO3 -] (+6.8 ± 1.6 mmo.l-1, d = 3.4, CI = 1.8, 4.7) compared with the PLA treatment, before TLIM2. It is likely both the acceleration of recovery, and the marked increases of acid-base after TLIM1 contributed to greater TLIM2 performance compared with the PLA condition.
Lewis A. Gough, Steven Rimmer, Callum J. Osler and Matthew F. Higgins
Marte Bentzen, Nicolas Lemyre and Göran Kenttä
The purpose of the current study was to provide insights in how and why four head coaches in elite football experienced being either high or low in burnout symptoms (BS) during a competitive season. A longitudinal sequential quantitative-qualitative mixed method approach was used to enhance the understanding of coaches’ experiences. First, data were collected using online questionnaires at the start and at the end of the competitive season with all coaches working at the Norwegian Elite Football League level. Second, in-depth interviews were conducted with four head coaches who were purposefully selected based on having the two highest and the two lowest burnout scores across the season compared with the overall sample. A quantitative approach was used to explore whether these four coaches differed when compared with the overall population on the associated variables: performance, budget, quality of motivation, perceived workload, work-home-interference (WHI), and recovery. A qualitative approach helped gain more insight in the experiences these four coaches had with possible onset variables. Analyses comparing the two sets of coaches, indicated no difference related to performance, budget and workload. However, the motivational profile, WHI, and ability to meet recovery demands were variables that contributed to explain differences in coaches’ BS.
Stephen P. Bird
Edited by Jennifer Medina McKeon
Adam U. Upshaw, Tiffany S. Wong, Arash Bandegan and Peter W.R. Lemon
Postexercise chocolate milk ingestion has been shown to enhance both glycogen resynthesis and subsequent exercise performance. To assess whether nondairy chocolate beverage ingestion post–glycogen-lowering exercise can enhance 20-km cycling time trial performance 4 hr later, eight healthy trained male cyclists (21.8 ± 2.3y, VO2max = 61.2 ± 1.4 ml·kg-1·min-1; M ± SD) completed a series of intense cycling intervals designed to lower muscle glycogen (Jentjens & Jeukendrup, 2003) followed by 4 hr of recovery and a subsequent 20-km cycling time trial. During the first 2 hr of recovery, participants ingested chocolate dairy milk (DAIRYCHOC), chocolate soy beverage (SOYCHOC), chocolate hemp beverage (HEMPCHOC), low-fat dairy milk (MILK), or a low-energy artificially sweetened, flavored beverage (PLACEBO) at 30-min intervals in a double-blind, counterbalanced repeated-measures design. All drinks, except the PLACEBO (247 kJ) were isoenergetic (2,107 kJ), and all chocolate-flavored drinks provided 1-g CHO·kg body mass-1·h-1. Fluid intake across treatments was equalized (2,262 ± 148 ml) by ingesting appropriate quantities of water based on drink intake. The CHO:PRO ratio was 4:1, 1.5:1, 4:1, and 6:1 for DAIRYCHOC, MILK, SOYCHOC, and HEMPCHOC, respectively. One-way analysis of variance with repeated measures showed time trial performance (DAIRYCHOC = 34.58 ± 2.5 min, SOYCHOC = 34.83 ± 2.2 min, HEMPCHOC = 34.88 ± 1.1 min, MILK = 34.47 ± 1.7 min) was enhanced similarly vs PLACEBO (37.85 ± 2.1) for all treatments (p = .019) These data suggest that postexercise macronutrient and total energy intake are more important for same-day 20-km cycling time trial performance after glycogen-lowering exercise than protein type or protein-to-carbohydrate ratio.
Greg J. Chertok and Ira H. Martin
Tarik Ozmen, Mert Aydogmus, Hanife Dogan, Derya Acar, Tuba Zoroglu and Mark Willems
Kinesio taping (KT) is a taping technique extensively used in rehabilitation of sports injuries; however, the effect of KT on delayed-onset muscle soreness is not entirely clear.
To investigate the effect of kinesio tape on the quadriceps femoris on muscle pain, flexibility, and sprint performance after squat exercise.
University research laboratory.
19 female university students (age 21.0 ± 1.2 y, weight 53.0 ± 4.6 kg, height 164 ± 4 cm).
Main Outcome Measures:
Pressure-pain threshold for quadriceps femoris was recorded using pressure algometry. Quadriceps femoris flexibility was measured as the range of motion of knee flexion with a stainless steel goniometer. Sprint-speed measurements were conducted using photocells placed at 0 and 20 m. All participants completed both conditions (KT application and no KT application) after a 1-wk washout period. Measurements were taken at baseline and 48 h postexercise. For the KT condition, KT was applied immediately before the exercise protocol and remained on the skin for 48 h.
Squat exercise reduced flexibility and increased pain and sprint time compared with baseline. KT application resulted in similar sprint time and muscle pain as the no-KT condition but maintained flexibility compared with baseline.
KT application immediately before squat exercise has no effect on muscle pain and short sprint performance but maintains muscle flexibility at 2 days of recovery.
Flatwater kayaking requires upper-body muscle strength and a lean body composition. This case study describes a nutrition intervention with a 19-year-old male elite sprint kayaker to increase muscle mass and improve recovery posttraining. Before the intervention, average daily energy intake was 13.6 ± 2.5 MJ (M ± SD; protein, 1.8 g/kg; carbohydrate, 3.6 g/kg), and the athlete was unable to eat sufficient food to meet the energy demands of training. During the 18-month intervention period, the athlete’s daily energy intake increased to 22.1 ± 3.8 MJ (protein, 3.2 g/kg; carbohydrate, 7.7 g/kg) by including milk-based drinks pre- and posttraining and before bed and an additional carbohydrate-based snack midmorning. This simple dietary intervention, along with a structured strength and conditioning program, resulted in an increase of 10 kg body mass with minimal change in body fat percentage. Adequate vitamin D status was maintained without the need for supplementation during the intervention period. In addition, the athlete reported the milk-based drinks and carbohydrate snacks were easy to consume, and no adverse side effects were experienced. This was the first time the athlete was able to maintain weight during intensive phases of the training cycle.
Vanessa Martínez-Lagunas and Ulrich Hartmann
To evaluate the validity of the Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) for the direct assessment and the indirect estimation of maximal oxygen consumption (VO2max) in female soccer players compared with a maximal laboratory treadmill test (LTT).
Eighteen female soccer players (21.5 ± 3.4 y, 165.6 ± 7.5 cm, 63.3 ± 7.4 kg; mean ± SD) completed an LTT and a YYIR1 in random order (1 wk apart). Their VO2max was directly measured via portable spirometry during both tests and indirectly estimated from a published non-gender-specific formula (YYIR1-F1).
The measured VO2max values in LTT and YYIR1 were 55.0 ± 5.3 and 49.9 ± 4.9 mL · kg−1 · min−1, respectively, while the estimated VO2max values from YYIR1-F1 corresponded to 45.2 ± 3.4 mL · kg−1 · min−1. Large positive correlations between the VO2max values from YYIR1 and LTT (r = .83, P < .001, 90% confidence interval = .64–.92) and YYIR1-F1 and LTT (r = .67, P = .002, .37–.84) were found. However, the YYIR1 significantly underestimated players’ VO2max by 9.4% compared with LTT (P < .001) with Bland-Altman 95% limits of agreement ranging from –20.0% to 1.4%. A significant underestimation from the YYIR1-F1 (P < .001) was also identified (17.8% with Bland-Altman 95% limits of agreement ranging from –31.8% to –3.8%).
The YYIR1 and YYIR1-F1 are not accurate methods for the direct assessment or indirect estimation of VO2max in female soccer players. The YYIR1-F1 lacks gender specificity, which might have been the reason for its larger error.
Mathew W.H. Inness, François Billaut and Robert J. Aughey
To determine the time course for physical-capacity adaptations to intermittent hypoxic training (IHT) in team-sport athletes and the time course for benefits remaining after IHT.
A pre–post parallel-groups design was employed, with 21 Australian footballers assigned to IHT (n = 10) or control (CON; n = 11) matched for training load. IHT performed eleven 40-min bike sessions at 2500-m altitude over 4 wk. Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) was performed before; after 3, 6, and 11 IHT sessions; and 30 and 44 d after IHT. Repeated time trials (2- and 1-km TTs, with 5 min rest) were performed before, after, and 3 wk after IHT. Hemoglobin mass (Hbmass) was measured in IHT before and after 3, 6, 9, and 11 sessions.
Baseline Yo-Yo IR2 was similar between groups. After 6 sessions, the change in Yo-Yo IR2 in IHT was very likely higher than CON (27% greater change, effect size 0.77, 90% confidence limits 0.20;1.33) and likely higher 1 d after IHT (23%, 0.68, 0.05;1.30). The IHT group’s change remained likely higher than CON 30 d after IHT (24%, 0.72, 0.12;1.33) but was not meaningfully different 44 d after (12%, 0.36, –0.24;0.97). The change in 2-km TT performance between groups was not different throughout. For 1-km TT, CON improved more after IHT, but IHT maintained performance better after 3 wk. Hbmass was higher after IHT (2.7%, 0.40, –0.40;1.19).
Short-duration IHT increased Yo-Yo IR2 compared with training-load-matched controls in 2 wk. An additional 2 wk of IHT provided no further benefit. These changes remained until at least 30 d posttraining. IHT also protected improvement in 1-km TT.
Maria Grazia Benedetti, Lisa Berti, Antonio Frizziero, Donata Ferrarese and Sandro Giannini
Surface replacement of the hip is aimed especially at active patients, and it seems to achieve optimal functional results in a short time if associated with a tailored rehabilitation protocol.
To assess the functional outcome in a group of active patients after hip resurfacing.
Clinical measurement and controlled laboratory study in a case series.
8 patients and a control group of 10 subjects.
Patients treated with Birmingham hip-resurfacing system and a tailored rehabilitation protocol
Main Outcome Measures:
Clinical assessment (Harris Hip Score [HHS]) and instrumented gait analysis including muscular electromyographic assessment. Patients were assessed preoperatively and at 3 and 9 mo follow-up after surgery.
HHS showed a significant increase from the baseline to 3- (P = .008) and 9-month (P = .014) follow-up; 5 patients returned to sport. Gait pattern in the presented case series of patients improved substantially 3 mo postoperatively, and minimal further changes were present 9 months postoperatively. Residual abnormalities of time-distance and hip-kinematics parameters were consistent with a slow gait. A complete restoration of the muscle-activation pattern during gait was achieved.
Hip resurfacing associated with a rehabilitation protocol based on the characteristics of the implant provides excellent clinical and functional outcome, especially for very active patients.