Physical responses of different small-sided game formats in elite youth soccer players

A major use of small-sided games (SSGs) in soccer training is the concomitant development of game-specific aerobic fitness. We hypothesize that the SSG formats of 2 vs. 2, 3 vs. 3, and 4 vs. 4 players reveal game-like intensities and therefore are most adequate to increase game-specific aerobic fitness. Heart rate (HR), percentage of maximum heart rate (HRmax), blood lactate concentration (La), and time-motion characteristics of 17 elite male youth soccer players (aged 14.9 ± 0.7 years, V[Combining Dot Above]O2max 61.4 ± 4.5 ml·kg·min, HRmax 199.6 ± 7.3 b·min) were collected by global positioning systems while performing the SSG formats. Repeated-measures analysis of variance and effect sizes were calculated to demonstrate the differences between SSG formats. Highest physiological responses were obtained in 2 vs. 2 (HR: 186 ± 7 b·min, HRmax: 93.3 ± 4.2%, La: 5.5 ± 2.4 mmol·L) followed by 3 vs. 3 (HR: 184 ± 8 b·min, HRmax: 91.5 ± 3.3%, La: 4.3 ± 1.7 mmol·L) and 4 vs. 4 (HR: 179 ± 7 b·min, HRmax 89.7 ± 3.4%, La: 4.4 ± 1.9 mmol·L). Pronounced differences were found for most physiological parameters and for time spent in the speed zones "walking" (<5.3 km·h), "moderate-speed running" (10.3-13.9 km·h), and "maximum sprinting" (≥26.8 km·h). The findings suggest that all the formats reveal game-like intensities and are suitable for aerobic fitness improvements. However, we found pronounced demands on the anaerobic energy supply in 2 vs. 2, whereas 3 vs. 3 and 4 vs. 4 remain predominantly on an aerobic level and differ mainly in the HR response. We suggest using 3 vs. 3 for soccer-specific aerobic fitness training.     

Effects of playing surface (hard and clay courts) on heart rate and blood lactate during tennis matches played by high-level players

The aim of this study was to compare tennis matches played on clay (CL) and resin (R) courts. Six matches were played (3 on CL courts and 3 on R courts) by 6 high-level players. Heart rate (HR) was monitored continuously while running time (4.66 m), and blood lactate concentration ([La]) were measured every 4 games. Mean duration of points and effective playing time (EPT) were measured for each match. Mean HR (154 ± 12 vs. 141 ± 9 b · min(-1)) and [La] values (5.7 ± 1.8 vs. 3.6 ± 1.2 mmol · L(-1)) were significantly higher on CL (p < 0.05). The [La] increased significantly during the match on CL court. Mean duration of rallies (8.5 ± 0.2 vs. 5.9 ± 0.5 seconds) and EPT (26.2 ± 1.9 vs. 19.5 ± 2.0%) were significantly longer (p < 0.05) on CL. Running time values in speed tests were not significantly different between CL and R. Running time performance was not significantly decreased during the match, whatever the playing surface. This study shows that the court surface influences the characteristics of the match and the player's physiological responses. The court surface should be a key factor for consideration when coaches determine specific training programs for high-level tennis players.     

Heart rate and perceived exertion during self-selected intensities for exergaming compared to traditional exercise in college-age participants

Exergames may be useful for promoting physical activity in younger populations. Heart rate (HRs) responses and rating of perceived exertion (RPE) at self-selected intensities were compared in college-age participants during 2 modes of exergame activity vs. traditional exercise. Thirty-seven participants (men: 20, women: 17) completed 3 30-minute self-selected intensity trials: (a) video game interactive bicycle ergometer (GB) (CatEye GB300), (b) interactive video dance game (Dance Dance Revolution [DDR]), and (c) traditional cycle ergometer (CE) while watching television. Mean HR, peak HR (PkHR), and minutes above target HR (THR) were significantly higher for GB (144 ± 22 b · min(-1) [57% HR reserve (HRR)], 161 ± 23 b · min(-1), and 22.5 ± 11.1 minutes) than for DDR (119 ± 16 b · min(-1) [37% HRR], 138 ± 20 b · min(-1), and 11.2 ± 11.9 minutes) or for CE (126 ± 20 b · min(-1) [42% HRR], 144 ± 24 b · min(-1), and 14.2 ± 12.6 minutes). The RPE was significantly higher for GB (4.2 ± 1.5) and CE (3.8 ± 1.2) than for DDR (2.7 ± 1.3). Recovery HR (RecHR) (15 minutes postexercise) was significantly higher for GB (91 ± 14 b · min(-1)) than for DDR (80 ± 11 b · min(-1)) and neared significance vs. CE (84 ± 14 b · min(-1), p = 0.059). No difference in PkHR, RecHR, or minutes above THR was observed between DDR and CE. Session RPE was significantly higher for GB (4.6 ± 1.7) and CE (4.1 ± 1.6) than for DDR (2.8 ± 1.5). All modes elicited extended proportions of time above THR; GB: 75%, DDR: 37%, and CE: 47%. Results support that exergames are capable of eliciting physiological responses necessary for fitness improvements. Practitioners might consider exergames as periodic activity options for clients needing motivation to be regularly active.     

Exercise training augments the dynamic heart rate response to vagal but not sympathetic stimulation in rats

We examined the transfer function of autonomic heart rate (HR) control in anesthetized sedentary and exercise-trained (16 wk, treadmill for 1 h, 5 times/wk at 15 m/min and 15-degree grade) rats for comparison to HR variability assessed in the conscious resting state. The transfer function from sympathetic stimulation to HR response was similar between groups (gain, 4.2 ± 1.5 vs. 4.5 ± 1.5 beats·min(-1)·Hz(-1); natural frequency, 0.07 ± 0.01 vs. 0.08 ± 0.01 Hz; damping coefficient, 1.96 ± 0.55 vs. 1.69 ± 0.15; and lag time, 0.7 ± 0.1 vs. 0.6 ± 0.1 s; sedentary vs. exercise trained, respectively, means ± SD). The transfer gain from vagal stimulation to HR response was 6.1 ± 3.0 in the sedentary and 9.7 ± 5.1 beats·min(-1)·Hz(-1) in the exercise-trained group (P = 0.06). The corner frequency (0.11 ± 0.05 vs. 0.17 ± 0.09 Hz) and lag time (0.1 ± 0.1 vs. 0.2 ± 0.1 s) did not differ between groups. When the sympathetic transfer gain was averaged for very-low-frequency and low-frequency bands, no significant group effect was observed. In contrast, when the vagal transfer gain was averaged for very-low-frequency, low-frequency, and high-frequency bands, exercise training produced a significant group effect (P < 0.05 by two-way, repeated-measures ANOVA). These findings suggest that, in the frequency domain, exercise training augments the dynamic HR response to vagal stimulation but not sympathetic stimulation, regardless of the frequency bands.     

Maximal lactate steady-state independent of recovery period during intermittent protocol

Barbosa, LF, de Souza, MR, Corrêa Caritá, RA, Caputo, F, Denadai, BS, and Greco, CC. Maximal lactate steady-state independent of recovery period during intermittent protocol. J Strength Cond Res 25(12): 3385-3390, 2011-The purpose of this study was to analyze the effect of the measurement time for blood lactate concentration ([La]) determination on [La] (maximal lactate steady state [MLSS]) and workload (MLSS during intermittent protocols [MLSSwi]) at maximal lactate steady state determined using intermittent protocols. Nineteen trained male cyclists were divided into 2 groups, for the determination of MLSSwi using passive (VO(2)max = 58.1 ± 3.5 ml·kg·min; N = 9) or active recovery (VO(2)max = 60.3 ± 9.0 ml·kg·min; N = 10). They performed the following tests, in different days, on a cycle ergometer: (a) Incremental test until exhaustion to determine (VO(2)max and (b) 30-minute intermittent constant-workload tests (7 × 4 and 1 × 2 minutes, with 2-minute recovery) to determine MLSSwi and MLSS. Each group performed the intermittent tests with passive or active recovery. The MLSSwi was defined as the highest workload at which [La] increased by no more than 1 mmol·L between minutes 10 and 30 (T1) or minutes 14 and 44 (T2) of the protocol. The MLSS (Passive-T1: 5.89 ± 1.41 vs. T2: 5.61 ± 1.78 mmol·L) and MLSSwi (Passive-T1: 294.5 ± 31.8 vs. T2: 294.7 ± 32.2 W; Active-T1: 304.6 ± 23.0 vs. T2: 300.5 ± 23.9 W) were similar for both criteria. However, MLSS was lower in T2 (4.91 ± 1.91 mmol·L) when compared with in T1 (5.62 ± 1.83 mmol·L) using active recovery. We can conclude that the MLSSwi (passive and active conditions) was unchanged whether recovery periods were considered (T1) or not (T2) for the interpretation of [La] kinetics. In contrast, MLSS was lowered when considering the active recovery periods (T2). Thus, shorter intermittent protocols (i.e., T1) to determine MLSSwi may optimize time of the aerobic capacity evaluation of well-trained cyclists.     

Achievement of v[combining dot above]o2max criteria during a continuous graded exercise test and a verification stage performed by college athletes

ABSTRACT: Mier, CM, Alexander, RP, and Mageean, AL. Achievement of V[Combining Dot Above]O2max criteria during a continuous graded exercise test and a verification stage performed by college athletes. J Strength Cond Res 26(10): 2648-2654, 2012-The purpose of this study was to determine the incidence of meeting specific V[Combining Dot Above]O2max criteria and to test the effectiveness of a V[Combining Dot Above]O2max verification stage in college athletes. Thirty-five subjects completed a continuous graded exercise test (GXT) to volitional exhaustion. The frequency of achieving various respiratory exchange ratio (RER) and age-predicted maximum heart rate (HRmax) criteria and a V[Combining Dot Above]O2 plateau within 2 and 2.2 ml·kg·min (<2SD of the expected increase in V[Combining Dot Above]O2) were measured and tested against expected frequencies. After 10 minutes of active recovery, 10 subjects who did not demonstrate a plateau completed a verification stage performed at supramaximal intensity. From the GXT, the number of subjects meeting V[Combining Dot Above]O2max plateau was 5 (≤2 ml·kg·min) and 7 (≤2.2 ml·kg·min), RER criteria 34 (≥1.05), 32 (≥1.10), and 24 (≥1.15), HRmax criteria, 35 (<85%), 29 (<10 b·min) and 9 (HRmax). The V[Combining Dot Above]O2max and HRmax did not differ between GXT and the verification stage (53.6 ± 5.6 vs. 55.5 ± 5.6 ml·kg·min and 187 ± 7 vs. 187 ± 6 b·min); however, the RER was lower during the verification stage (1.15 ± 0.06 vs. 1.07 ± 0.07, p = 0.004). Six subjects achieved a similar V[Combining Dot Above]O2 (within 2.2 ml·kg·min), whereas 4 achieved a higher V[Combining Dot Above]O2 compared with the GXT. These data demonstrate that a continuous GXT limits the college athlete's ability to achieve V[Combining Dot Above]O2max plateau and certain RER and HR criteria. The use of a verification stage increases the frequency of V[Combining Dot Above]O2max achievement and may be an effective method to improve the accuracy of V[Combining Dot Above]O2max measurements in college athletes.     

Effect of expertise on postmaximal long sprint blood metabolite responses

The aim of this study was to describe and compare the blood metabolic responses obtained after a single maximal exercise in elite and less-successful athletes and to investigate whether these responses are related to sprint performance. Eleven elite (ELI) and 14 regional (REG) long sprint runners performed a 300-m running test as fast as possible. Blood samples were taken at rest and at 4 minutes after exercise for measurements of blood lactate concentration [La] and acid-base status. The blood metabolic responses of ELI subjects compared to those of REG subjects for pH (7.07 ± 0.05 vs. 7.14 ± 1.5), sodium bicarbonate concentration ([HCO(3)(-)], 8.1 ± 1.5 vs. 9.8 ± 1.8 mmol·L(-1)), hemoglobin O(2) saturation (SaO(2)) (94.7 ± 1.8 vs. 96.2 ± 1.6%) were significantly lower (p < 0.05), and [La] was significantly higher in ELI (21.1 ± 2.9 vs. 19.1 ± 1.2 mmol·L(-1), p < 0.05). The 300-m performance (in % world record) was negatively correlated with pH (r = -0.55, p < 0.01), SaO2 (r = -0.64, p < 0.001), [HCO(3)(-)] (r = -0.40, p < 0.05), and positively correlated with [La] (r = 0.44, p < 0.05). In conclusion, for the same quantity of work, the best athletes are able to strongly alter their blood acid-base balance compared to underperforming runners, with larger acidosis and lactate accumulation. To obtain the pH limits with acute maximal exercise, coaches must have their athletes perform a distance run with duration of exercise superior to 35 seconds. The blood lactate accumulation values (mmol·L(-1)·s(-1)) recorded in this study indicate that the maximal glycolysis rate obtained in the literature from short sprint distances is maintained, but not increased, until 35 seconds of exercise.     

Impact of gender on the cardiac autonomic response to angiotensin II in healthy humans

Premenopausal women have a lower risk of cardiovascular disease (CVD) compared with men of a similar age. Furthermore, the regulation of factors that influence CVD appears to differ between the sexes, including control of the autonomic nervous system (ANS) and the renin-angiotensin system. We examined the cardiac ANS response to angiotensin II (Ang II) challenge in healthy subjects to determine whether differences in women and men exist. Thirty-six healthy subjects (21 women, 15 men, age 38 ± 2 years) were studied in a high-salt balance. Heart-rate variability (HRV) was calculated by spectral power analysis [low-frequency (LF) sympathetic modulation, high-frequency (HF) parasympathetic/vagal modulation, and LF:HF as a measure of overall ANS balance]. HRV was assessed at baseline and in response to graded Ang II infusions (3 ng·kg(-1)·min(-1) × 30 min; 6 ng·kg(-1)·min(-1) × 30 min). Cardiac ANS tone did not change significantly in women after each Ang II dose [3 ng·kg(-1)·min(-1) mean change (Δ)LF:HF (mean ± SE) 0.5 ± 0.3, P = 0.8, vs. baseline; 6 ng·kg(-1)·min(-1) ΔLF:HF (mean ± SE) 0.5 ± 0.4, P = 0.4, vs. baseline], whereas men exhibited an unfavorable shift in overall cardiac ANS activity in response to Ang II (ΔLF:HF 2.6 ± 0.2, P = 0.01, vs. baseline; P = 0.02 vs. female response). This imbalance in sympathovagal tone appeared to be largely driven by a withdrawal in cardioprotective vagal activity in response to Ang II challenge [ΔHF normalized units (nu), -5.8 ± 2.9, P = 0.01, vs. baseline; P = 0.006 vs. women] rather than an increase in sympathetic activity (ΔLF nu, -4.5 ± 5.7, P = 0.3, vs. baseline; P = 0.5 vs. women). Premenopausal women maintain cardiac ANS tone in response to Ang II challenge, whereas similarly aged men exhibit an unfavorable shift in cardiovagal activity. Understanding the role of gender in ANS modulation may help guide risk-reduction strategies in high-risk CVD populations.     

Effects of a 6-week plyometric training program on performances in pubescent swimmers

This study examined in pubescent swimmers the effects on front crawl performances of a 6-week plyometric training (PT) in addition to the habitual swimming program. Swimmers were assigned to a control group (n = 11, age: 14.1 ± 0.2 years; G(CONT)) and a combined swimming and plyometric group (n = 12, age: 14.3 ± 0.2 years; GSP), both groups swimming 5.5 h · wk(-1) during a 6-week preseason training block. In the GSP, PT consisted of long, lateral high and depth jumps before swimming training 2 times per week. Pre and posttests were performed by jump tests (squat jump [SJ], countermovement jump [CMJ]) and swim tests: a gliding task, 400- and 50-m front crawl with a diving start (V400 and V50, m · s(-1)), and 2 tests with a water start without push-off on the wall (25 m in front crawl and 25 m only with kicks). Results showed improvement only for GSP for jump tests (Δ = 4.67 ± 3.49 cm; Δ = 3.24 ± 3.17 cm; for CMJ and SJ, respectively; p < 0.05) and front crawl tests (Δ = 0.04 ± 0.04 m · s(-1); Δ = 0.04 ± 0.05 m · s(-1); for V50 and V400, respectively; p < 0.05). Significant correlations were found for GSP between improvements in SJ and V50 (R = 0.73, p < 0.05). Results suggested a positive effect of PT on specific swimming tasks such as dive or turn but not in kicking propulsion. Because of the practical setup of the PT and the relevancy of successful starts and turns in swimming performances, it is strongly suggested to incorporate PT in pubescent swimmers' training and control it by jump performances.     

Intramyocellular lipid content and insulin sensitivity are increased following a short-term low-glycemic index diet and exercise intervention

The relationship between intramyocellular (IMCL) and extramyocellular lipid (EMCL) accumulation and skeletal muscle insulin resistance is complex and dynamic. We examined the effect of a short-term (7-day) low-glycemic index (LGI) diet and aerobic exercise training intervention (EX) on IMCL and insulin sensitivity in older, insulin-resistant humans. Participants (66 ± 1 yr, BMI 33 ± 1 kg/m(2)) were randomly assigned to a parallel, controlled feeding trial [either an LGI (LGI/EX, n = 7) or high GI (HGI/EX, n = 8) eucaloric diet] combined with supervised exercise (60 min/day, 85% HR(max)). Insulin sensitivity was determined via 40 mU·m(-2)·min(-1) hyperinsulinemic euglycemic clamp and soleus IMCL and EMCL content was assessed by (1)H-MR spectroscopy with correction for fiber orientation. BMI decreased (kg/m(2) -0.6 ± 0.2, LGI/EX; -0.7 ± 0.2, HGI/EX P < 0.0004) after both interventions with no interaction effect of diet composition. Clamp-derived insulin sensitivity increased by 0.91 ± 0.21 (LGI/EX) and 0.17 ± 0.55 mg·kg(-1)·min(-1) (HGI/EX), P = 0.04 (effect of time). HOMA-IR was reduced by -1.1 ± 0.4 (LGI/EX) and -0.1 ± 0.2 (HGI/EX), P = 0.007 (effect of time), P = 0.02 (time × trial). Although both interventions increased IMCL content, (Δ: 2.3 ± 1.3, LGI/EX; 1.4 ± 0.9, HGI/EX, P = 0.03), diet composition did not significantly effect the increase. However, the LGI/EX group showed a robust increase in the [IMCL]/[EMCL] ratio compared with the HGI/EX group (Δ: 0.5 ± 0.2 LGI/EX vs. 0.07 ± 0.1, P = 0.03). The LGI/EX group also demonstrated greater reductions in [EMCL] than the HGI/EX group (Δ: -5.8 ± 3.4, LGI/EX; 2.3 ± 1.1, HGI/EX, P = 0.03). Changes in muscle lipids and insulin sensitivity were not correlated; however, the change in [IMCL]/[EMCL] was negatively associated with the change in FPI (r = -0.78, P = 0.002) and HOMA-IR (r = -0.61, P = 0.03). These data suggest that increases in the IMCL pool following a low glycemic diet and exercise intervention may represent lipid repartitioning from EMCL. The lower systemic glucose levels that prevail while eating a low glycemic diet may promote redistribution of lipid stores in the muscle.     

Moderate weight loss improves heart rate variability in overweight and obese adults with type 2 diabetes

The objective of this study was to determine the effects of weight loss on heart rate variability (HRV) and its association with traditional cardiovascular disease risk factors in overweight and obese patients with type 2 diabetes. Forty five patients [body mass index (BMI) 35.4 ± 0.7 kg/m2; age 56.5 ± 1.1 yr] with type 2 diabetes followed an energy-restricted diet (6-7 MJ/day) for 16 wk. Body weight, blood pressure, glucose, insulin, insulin resistance [homeostasis model assessment index 2 (HOMA2)], glycosylated hemoglobin (HbA1c), total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), triglycerides, resting HR, and HRV were measured before and after the intervention period. Mean reduction in body weight was 11.1 ± 1.0 kg (10%), with significant reductions in blood pressure (-10%), total cholesterol (-15.9%), LDL (-17.7%), HDL (-7.5%), triglycerides (-21.2%), glucose (-23.4%), insulin (-37.6%), HOMA2 (-40.1%), and HbA1c (-14.5%) (P ≤ 0.05 for all variables). There were increases in several HRV components, including total power (1,370 ± 280 to 2,045 ± 280 ms2), low-frequency power (345 ± 70 to 600 ± 108 ms2), SD of normal to normal intervals (SDNN; 35.0 ± 2.5 to 43.0 ± 2.7 s), and square root of the mean squared differences of successive normal to normal intervals (RMSSD; 23.0 ± 3.5 to 32.0 ± 3.1 s), and a decrease in HR (69.0 ± 1.3 to 60.0 ± 1.2 beats/min) (P ≤ 0.03 for all variables). Changes in HR, SDNN, total power, and low-frequency power correlated with change in BMI (P < 0.05). In addition to improvements in traditional cardiovascular and metabolic risk factors, weight loss improves HRV in overweight and obese patients with type 2 diabetes.     

VO₂ requirements of boxing exercises

The purpose of this study was to quantify the physiological requirements of various boxing exercises such as sparring, pad work, and punching bag. Because it was not possible to measure the oxygen uptake (VO?) of "true" sparring with a collecting gas valve in the face, we developed and validated a method to measure VO? of "true" sparring based on "postexercise" measurements. Nine experienced male amateur boxers (Mean ± SD: age = 22.0 ± 3.5 years, height = 176.0 ± 8.0 cm, weight = 71.4 ± 10.9 kg, number of fights = 13.0 ± 9.5) of regional and provincial level volunteered to participate in 3 testing sessions: (a) maximal treadmill test in the LAB, (b) standardized boxing training in the GYM, and (c) standardized boxing exercises in the LAB. Measures of VO?, heart rate (HR), blood lactate concentration [LA], rated perceived exertion level, and punching frequencies were collected. VO? values of 43.4 ± 5.9, 41.1 ± 5.1, 24.7 ± 6.1, 30.4 ± 5.8, and 38.3 ± 6.5 ml·kg?1·min?1 were obtained, which represent 69.7 ± 8.0, 66.1 ± 8.0, 39.8 ± 10.4, 48.8 ± 8.5, and 61.7 ± 10.3%VO?peak for sparring, pad work, and punching bag at 60, 120, and 180 b·min?1, respectively. Except for lower VO? values for punching the bag at 60 and 120 b·min?1 (p < 0.05), there was no VO? difference between exercises. Similar pattern was obtained for %HRmax with respective values of 85.5 ± 5.9, 83.6 ± 6.3, 67.5 ± 3.5, 74.8 ± 5.9, and 83.0 ± 6.0. Finally, sparring %HRmax and [LA] were slightly higher in the GYM (91.7 ± 4.3 and 9.4 ± 2.2 mmol·L?1) vs. LAB (85.5 ± 5.9 and 6.1 ± 2.3 mmol·L?1). Thus, in this study simulated LAB sparring and pad work required similar VO? (43-41 ml·kg?1·min?1, respectively), which corresponds to ~70%VO?peak. These results underline the importance of a minimum of aerobic fitness for boxers and draw some guidelines for the intensity of training.     

Muscle cellular properties in the ice hockey player: a model for investigating overtraining?

In this study, we hypothesized that athletes involved in 5-6 months of sprint-type training would display higher levels of proteins and processes involved in muscle energy supply and utilization. Tissue was sampled from the vastus lateralis of 13 elite ice hockey players (peak oxygen consumption = 51.8 ± 1.3 mL·kg(-1)·min(-1); mean ± standard error) at the end of a season (POST) and compared with samples from 8 controls (peak oxygen consumption = 45.5 ± 1.4 mL·kg(-1)·min(-1)) (CON). Compared with CON, higher activities were observed in POST (p < 0.05) only for succinic dehydrogenase (3.32 ± 0.16 mol·(mg protein)(-1)·min(-1) vs. 4.10 ± 0.11 mol·(mg protein)(-1)·min(-1)) and hexokinase (0.73 ± 0.05 mol·(mg protein)(-1)·min(-1) vs. 0.90 ± 0.05mol·(mg protein)(-1)·min(-1)) but not for phosphorylase, phosphofructokinase, and creatine phosphokinase. No differences were found in Na(+),K(+)-ATPase concentration (β(max): 262 ± 36 pmol·(g wet weight)(-1) vs. 275 ± 27 pmol·(g wet weight)(-1)) and the maximal activity of the sarcoplasmic reticulum Ca(2+)-ATPase (98.1 ± 6.1 μmol·(g protein)(-1)·min(-1) vs. 102 ± 3.3 μmol·(g protein)(-1)·min(-1)). Cross-sectional area was lower (p < 0.05) in POST but only for the type IIA fibres (6312 ± 684 μm(2) vs. 5512 ± 335 μm(2)), while the number of capillary counts per fibre and the capillary to fibre area ratio were generally higher (p < 0.05). These findings suggest that elite trained ice hockey players display elevations only in support of glucose-based aerobic metabolism that occur in the absence of alterations in excitation-contraction processes.     

Do compression garments enhance the active recovery process after high-intensity running?

Lovell, DI, Mason, DG, Delphinus, EM, and McLellan, CP. Do compression garments enhance the active recovery process after high-intensity running? J Strength Cond Res 25(12): 3264-3268, 2011-This study examined the effect of wearing waist-to-ankle compression garments (CGs) on active recovery after moderate- and high-intensity submaximal treadmill running. Twenty-five male semiprofessional rugby league players performed two 30-minute treadmill runs comprising of six 5-minute stages at 6 km·h, 10 km·h, approximately 85% VO(2)max, 6 km·h as a recovery stage followed by approximately 85% VO(2)max and 6 km·h wearing either CGs or regular running shorts in a randomized counterbalanced order with each person acting as his own control. All stages were followed by 30 seconds of rest during which a blood sample was collected to determine blood pH and blood lactate concentration [La]. Expired gases and heart rate (HR) were measured during the submaximal treadmill tests to determine metabolic variables with the average of the last 2 minutes used for data analysis. The HR and [La] were lower (p ≤ 0.05) after the first and second 6 km·h recovery bouts when wearing CGs compared with when wearing running shorts. The respiratory exchange ratio (RER) was higher and [La] lower (p ≤ 0.05) after the 10 km·h stage, and only RER was higher after both 85% VO(2)max stages when wearing CGs compared with when wearing running shorts. There was no difference in blood pH at any exercise stage when wearing the CGs and running shorts. The results of this study indicate that the wearing of CGs may augment the active recovery process in reducing [La] and HR after high-intensity exercise but not effect blood pH. The ability to reduce [La] and HR has important consequences for many sports that are intermittent in nature and consist of repeated bouts of high-intensity exercise interspersed with periods of low-intensity exercise or recovery.     

Relationship between peripheral muscle structure and function in patients with chronic obstructive pulmonary disease with different nutritional status

The purpose of this study was to investigate the relationships between peripheral muscle structure (mass) and function (strength, endurance, and maximal aerobic capacity) in patients with chronic obstructive pulmonary disease (COPD) with different nutritional states. Thirty-nine patients (31 male) with moderate-severe COPD (63.5 ± 7.3 [SD] years) and 17 controls (14 male; 64.7 ± 5.5 [SD] years) underwent isokinetic (peak torque [PT]), isometric (isometric torque [IT]), and endurance strength (total work [TW]) measurements of the knee extensor muscles and a maximal cardiopulmonary exercise test to evaluate the maximal aerobic capacity (peak oxygen uptake [VO(2)] peak). Muscle mass (MM) was determined using dual-energy x-ray absorptiometry. Patients with COPD presented with reduced muscle function as compared with the healthy controls: PT (105.9 ± 33.9 vs. 134.3 ± 30.9, N·m(-1), respectively, p < 0.05), TW (1,446.3 ± 550.8 vs. 1,792.9 ± 469.1 kJ, respectively, p < 0.05), and VO(2)peak (68.1 ± 15.1 vs. 93.7 ± 14.5, % pred, respectively, p < 0.05). Significant relationships were found between muscle structure and function (strength and endurance) in the patient subgroup with preserved MM and in the control group: PT·MM(r(2) = 0.36; p = 0.01 vs. r(2) = 0.32; p = 0.01, respectively) and TW·MM (r(2) = 0.32; p = 0.01 vs. r(2) = 0.22; p = 0.05, respectively). Strength corrected for mass normalized this function in both patient subgroups, whereas endurance was normalized only in the patient subgroup without muscle depletion. Maximal aerobic capacity remained reduced, despite the correction, in both patient subgroups (depleted or nondepleted) compared with the healthy controls (VO(2)peak.MM: 9.1 ± 3.7 vs. 21.8 ± 4.9 vs. 28.5 ± 4.2 ml·min·kg, respectively, with p < 0.01 among groups). Muscle atrophy seems to be the main determinant of strength reduction among patients with moderate-severe COPD, whereas endurance reduction seems to be more related to imbalance between oxygen delivery and consumption than to the local muscle structure itself. Peripheral MM did not constitute a good predictor for maximal aerobic capacity in this population. The main practical application of this study is to point out a crucial role for the strategies able to ameliorate cardiorespiratory and muscular fitness in patients with COPD, even in those patients with preserved MM.     

Aging and factors related to running economy

The purpose of this study was to investigate the relationship that age has on factors affecting running economy (RE) in competitive distance runners. Fifty-one male and female subelite distance runners (Young [Y]: 18-39 years [n = 18]; Master [M]: 40-59 years [n = 22]; and Older [O]: 60-older [n = 11]) were measured for RE, step rate, lactate threshold (LT), VO2max, muscle strength and endurance, flexibility, power, and body composition. An RE test was conducted at 4 different velocities (161, 188, 215, and 241 m·min(-1)), with subjects running for 5 minutes at each velocity. The steady-state VO2max during the last minute of each stage was recorded and plotted vs. speed, and a regression equation was formulated. A 1 × 3 analysis of variance revealed no differences in the slopes of the RE regression lines among age groups (y = 0.1827x - 0.2974; R2 = 0.9511 [Y]; y = 0.1988x - 1.0416; R2 = 0.9697 [M]; y = 0.1727x + 3.0252; R2 = 0.9618 [O]). The VO2max was significantly lower in the O group compared to in the Y and M groups (Y = 64.1 ± 3.2; M = 56.8 ± 2.7; O = 44.4 ± 1.7 mlO2·kg(-1)·min(-1)). The maximal heart rate and velocity @ LT were significantly different among all age groups (Y = 197 ± 4; M = 183 ± 2; O = 170 ± 6 b·min(-1) and Y = 289.7 ± 27.0; M = 251.5 ± 32.9; O = 212.3 ± 24.6 m·min(-1), respectively). The VO2max @ LT was significantly lower in the O group compared to in the Y and M groups (Y = 50.3 ± 2.0; M = 48.8 ± 2.9; O = 34.9 ± 3.2 mlO2·kg(-1)·min(-1)). The O group was significantly lower than in the Y and M groups in flexibility, power, and upper body strength. Multiple regression analyses showed that strength and power were significantly related to running velocity. The results from this cross-sectional analysis suggest that age-related declines in running performance are associated with declines in maximal and submaximal cardiorespiratory variables and declines in strength and power, not because of declines in running economy.     

Post-competition blood lactate concentrations as indicators of anaerobic energy expenditure during 400-m and 800-m races

The relationships between anaerobic glycolysis and the average velocity (v) sustained during running were studied in 17 top level athletes (11 males and 6 females). A blood sample was obtained within 10 min of the completion of major competitions over 400 m, 800 m and 1500 m and the blood lactate concentration [la]b was measured. In both male and female athletes [la]b was related to the relative performance, as expressed as a percentage of the athlete's best v of the season. Over 400 m, r = 0.85 (P less than 0.01) and r = 0.80 (P less than 0.05) in males and females, respectively. Over 800 m, the corresponding values were r = 0.76 (P less than 0.01) and r = 0.91 (P less than 0.01). In male runners [la]b was correlated to v: r = 0.89 (P less than 0.01) and r = 0.71 (P less than 0.02) over 400 m and 800 m, respectively. No relationship to relative performance or v was obtained over 1500 m. Energy expenditure during competition running was estimated in male runners from the [la]b values. This estimate was based mainly on the assumption that a 1 mmol.1-1 increase in [la]b corresponded to the energy produced by the utilization of 3.30 ml.O kg-1. The energy cost of running was estimated, by dividing the estimated total energy expenditure by the race distance, at 0.211 ml.kg-1.min-1 over 800 m and 0.274 ml.kg-1.m-1 over 400 m.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of heart rate and session rating of perceived exertion methods of defining exercise load in cyclists

The aim of this study was to analyze the competition load using the session rating of perceived exertion (RPE) during different professional cycling races and to assess its validity using the competition load based on heart rate (HR). During 2 consecutive seasons, 12 professional cyclists (mean ± SEM: age 25 ± 1 years, height 175 ± 3 cm, body mass 65.9 ± 2.0 kg, and V(O2)max 78.5 ± 1.7 ml · kg(-1) · min(-1)) competed in 5-, 7-, and 21-day cycling races. The HR response and session RPE were measured during the races to calculate the competition load based on the training impulse of the HR (TRIMP(HR)) and RPE data (TRIMP(RPE)). The highest (p < 0.05) TRIMP(RPE) was observed in 21-day races. However, the higher (p < 0.05) TRIMP(HR) was found in 5- and 7-day races. When TRIMP(HR) and TRIMP(RPE) were normalized by competing distance, neither TRIMP(HR) · km(-1) nor TRIMP(RPE) · km(-1) was significantly different between the analyzed cycling races. We found significant (p < 0.001) correlations between TRIMP(HR) and TRIMP(RPE) (r = 0.75) and between TRIMP(HR) · km(-1) and TRIMP(RPE) · km(-1) (r = 0.90). In conclusion, this study showed that the session RPE can be used to quantify the competition load during professional cycling races. This method can be a useful and noninvasive tool for coaches to monitor and control the training load in cyclists.     

Match analysis of elite adolescent team handball players

The purposes of this study were to examine the activity profile of elite adolescent players during regular team handball games and to compare the physical and motor performance of players between the first and second halves of a match. Activity patterns (video analysis) and heart-rate (HR) responses (telemetry) were monitored in top national-division adolescent players (18 men, aged 15.1 ± 0.6 years) throughout 6 regulation games (25-minute halves with a 10-minute interval). The total distance covered averaged 1,777 ± 264 m per game (7.4% less in the second than in the first half, p > 0.05). Players ran 170 ± 24 m at high intensity and 86 ± 12 m at maximal speed, with 32 ± 6 bouts of running (duration 2.3 ± 0.3 seconds) at speeds > 18 km·h(-1); they stood still for 16% of the playing time. The mean HR during play was 172 ± 2 b·min(-1) (82 ± 3% of maximal HR). Blood lactate concentrations at the end of the first and second halves were 9.7 ± 1.1 and 8.3 ± 0.9 mmol·L(-1), respectively (difference p < 0.05). We conclude that adolescent handball players cover less distance and engage in fewer technical actions in the second half of a match. This indicates that team handball is physiologically very demanding. The practical implication is that coaches should seek to sustain performance in the second period of a game by modifying playing tactics and maximizing both aerobic and anaerobic fitness during training sessions.