Stroke phases responses around maximal lactate steady state in front crawl

The objective of this study was to analyze changes in stroke rate (SR), stroke length (SL) and stroke phases (entry and catch, pull, push and recovery) when swimming at (MLSS) and above (102.5% MLSS) the maximal lactate steady state. Twelve endurance swimmers (21±8 year, 1.77±0.10m and 71.6±7.7kg) performed in different days the following tests: (1) 200- and 400-m all-out tests, to determine critical speed (CS), and; (2) 2-4 30-min sub-maximal constant-speed tests, to determine the MLSS and 102.5% MLSS. There was significant difference among MLSS (1.22±0.05ms-1), 102.5% MLSS (1.25±0.04ms-1) and CS (1.30±0.08ms-1). SR and SL were maintained between the 10th and 30th minute of the test swum at MLSS and have modified significantly at 102.5% MLSS (SR - 30.9±3.4 and 32.2±3.5cyclesmin-1 and SL - 2.47±0.2 and 2.38±0.2mcycle-1, respectively). All stroke phases were maintained at 10th and 30th minute at MLSS. However, the relative duration of propulsive phase B (pull) increased significantly at 102.5% MLSS (21.7±3.4% and 22.9±3.9%, respectively). Therefore, the metabolic condition may influence the stroke parameters (SR and SL) and stroke strategy to maintain the speed during swim tests lasting 30min. © 2010 Sports Medicine Australia

EFFECTS OF GENDER ON STROKE RATES, CRITICAL SPEED AND VELOCITY OF A 30-MIN SWIM IN YOUNG SWIMMERS

Our objective was to analyze the effect of gender on the relationship between stroke rates corresponding to critical speed (SRCS) and maximal speed of 30 min (SRS30) in young swimmers. Twenty two males (GM1) (Age = 15.4 ± 2.1 yr., Body mass = 63.7 ± 12.9 kg, Stature = 1.73 ± 0.09 m) and fourteen female (GF) swimmers (Age = 15.1 ± 1.6 yr., Body mass = 58.3 ± 8.8 kg, Stature = 1.65 ± 0.06 m) were studied. A subset of males (GM2) was matched to the GF by their velocity for a 30 min swim (S30). The critical speed (CS) was determined through the slope of the linear regression line between the distances (200 and 400 m) and participant's respective times. CS was significantly higher than S30 in males (GM1 - 1.25 and 1.16 and GM2 - 1.21 and 1.12 m·s-1) and females (GF - 1.15 and 1.11 m·s-1). There was no significant difference between SRCS and SRS30 in males (GM1 - 34.16 and 32.32 and GM2 - 34.67 and 32.46 cycle·s-1, respectively) and females (GF - 34.18 and 33.67 cycle·s-1, respectively). There was a significant correlation between CS and S30 (GM1 - r = 0.89, GF - r = 0.94 and GM2 - r = 0.90) and between SRCS and SRS30 (GM1 - r = 0.89, GF - r = 0.80 and GM2 - r = 0.88). Thus, the relationship between SRCS and SRS30 is not influenced by gender, in swimmers with similar and different aerobic capacity level

Reliability of Cardiorespiratory Parameters During Cycling Exercise Performed at the Severe Domain in Active Individuals

Barbosa, LF, Montagnana, L, Denadai, BS, and Greco, CC. Reliability of cardiorespiratory parameters during cycling exercise performed at the severe domain in active individuals. J Strength Cond Res 28(4): 976-981, 2014-The purpose of this study was to determine the test-retest reliability of cardiorespiratory parameters during cycling exercise performed at severe domain in active individuals. Thirteen active males (24.5 +/- 4.5 years) performed the following tests: (a) an incremental test to determine V ̇o(2)max and the intensity associated with V ̇o(2)max (IV ̇o(2)max); and (b) 4 repetitions of square-wave transitions from rest to a power corresponding to 95%IV ̇o(2)max to determine the parameters of V ̇o(2) kinetics and time to exhaustion (Tlim). Participants performed only 2 transitions on any given day. The interval between the 2 experimental sessions was 48-72 hours. The intraclass correlation coefficient (ICC) and typical error as the coefficient of variation were used to assess reliability. Although the 2 measures of Tlim were moderately related (ICC = 0.78; p < 0.01), Tlim from the second session (545.2 +/- 103.1 seconds) was significantly higher than that of the first (492.5 +/- 100.9 seconds; p = 0.02). Moderate to high reliability (ICC = 0.76-0.93) for the amplitudes of the V ̇o(2) kinetics responses was found. Poor reliability, however, was found for time constants and time delays of the V ̇o(2) kinetics responses. Thus, in nonfamiliarized individuals, Tlim shows a relatively low within-subject coefficient of variation. However, the second score in a series of 2 Tlim tests may be significantly greater than the first. We have also demonstrated that the amplitudes of the V ̇o(2) response have significantly moderate to high reliability. The time-based parameters, however, present an important day-to-day intraindividual variation. Therefore, several transitions are recommended to monitoring changes in an individual over any time frame.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effects of gender on stroke rates, critical speed and velocity of a 30-min swim in young swimmers

Our objective was to analyze the effect of gender on the relationship between stroke rates corresponding to critical speed (SRCS) and maximal speed of 30 min (SRS30) in young swimmers. Twenty two males (GM1) (Age = 15.4 ± 2.1 yr., Body mass = 63.7 ± 12.9 kg, Stature = 1.73 ± 0.09 m) and fourteen female (GF) swimmers (Age = 15.1 ± 1.6 yr., Body mass = 58.3 ± 8.8 kg, Stature = 1.65 ± 0.06 m) were studied. A subset of males (GM2) was matched to the GF by their velocity for a 30 min swim (S30). The critical speed (CS) was determined through the slope of the linear regression line between the distances (200 and 400 m) and participant's respective times. CS was significantly higher than S30 in males (GM1 - 1.25 and 1.16 and GM2 - 1.21 and 1.12 m·s-1) and females (GF - 1.15 and 1.11 m·s-1). There was no significant difference between SRCS and SRS30 in males (GM1 - 34.16 and 32.32 and GM2 - 34.67 and 32.46 cycle·s-1, respectively) and females (GF - 34.18 and 33.67 cycle·s-1-1, respectively). There was a significant correlation between CS and S30 (GM1 - r = 0.89, GF - r = 0.94 and GM2 - r = 0.90) and between SRCS and SRS30 (GM1 - r = 0.89, GF - r = 0.80 and GM2 - r = 0.88). Thus, the relationship between SRCS and SRS30 is not influenced by gender, in swimmers with similar and different aerobic capacity levels. ©Journal of Sports Science and Medicine (2007)

How narrow is the spectrum of submaximal speeds in swimming?

The purpose of this study was to identify the boundary of submaximal speed zones (i.e., exercise intensity domains) between maximal aerobic speed (S-400) and lactate threshold (LT) in swimming. A 400-m all-out test, a 7 × 200 m incremental step test, and two to four 30-minute submaximal tests were performed by 12 male endurance swimmers (age = 24.5 ± 9.6 years; body mass = 71.3 ± 9.8 kg) to determine S-400, speed corresponding to LT, and maximal lactate steady state (MLSS). S-400 was 1.30 ± 0.09 m·s -1 (400 m-5:08 minutes:seconds). The speed at LT (1.08 ± 0.02 m·s-1; 83.1 ± 2.2 %S-400) was lower than the speed at MLSS (1.14 ± 0.02 m·s-1; 87.5 ± 1.9 %S-400). Maximal lactate steady state occurred at 26 ± 10% of the difference between the speed at LT and S-400. Mean blood lactate values at the speeds corresponding to LT and MLSS were 2.45 ± 1.13 mmol·L-1 and 4.30 ± 1.32 mmol·L-1, respectively. The present findings demonstrate that the range of intensity zones between LT and MLSS (i.e., heavy domain) and between MLSS and S-400 (i.e., severe domain) are very narrow in swimming with LT occurring at 83% S-400 in trained swimmers. Precision and sensitivity of the measurement of aerobic indexes (i.e., LT and MLSS) should be considered when conducting exercise training and testing in swimming. © 2013 National Strength and Conditioning Association

Effects of Exercise Mode on the Oxygen Uptake Kinetic Response to Severe-Intensity Exercise in Prepubertal Children

The objective of this study was to verify the effect of the exercise mode on slow component of VO(2) (VO(2)SC) in children aged 11-12 years during severe-intensity exercise. After determination of the lactate threshold (LT) and peak VO(2) (VO(2)peak) in both cycling (CE) and running exercise (TR), fourteen active boys completed a series of "square-wave" transitions of 6-min duration at 75%Delta [75%Delta = LT + 0.75 X (VO(2)peak-LT)l to determine the VO(2) kinetics. The VO(2)SC was significantly higher in CE (180.5 +/- 155.8 ml . min(-1)) than in TR (113.0 +/- 84.2 ml . min(-1)). We can conclude that, although a VO(2)SC does indeed develop during TR in children, its magnitude is considerably lower than in CE during severe-intensity exercise

Rapid hamstrings/quadriceps strength capacity in professional soccer players with different conventional isokinetic muscle strength ratios

Muscle strength imbalance can be an important factor in hamstrings muscle strain. A hamstrings/quadriceps (H/Q) strength ratio based on concentric peak torque values (H-con:Q(con)) has traditionally been used to describe the potential for knee-joint destabilization. Because certain standard actions in soccer are explosive, the analysis of the H/Q strength ratio based on the rate of torque development (H-rtd:Q(rtd)) might also be useful in the evaluation of joint stability. The objective of this study was to compare the H-rtd:Q(rtd) between professional soccer players with heterogeneous values of H-con:Q(con). Thirty-nine professional soccer players took part in the following procedures on different days: 1) Familiarization session with the isokinetic dynamometer, and 2) Two maximal isometric actions and five maximal concentric actions at 60 degrees.s(-1) for hamstrings (H) and quadriceps (Q). Participants were ranked according to their H-con:Q(con) ratio. The median third was excluded to form a high torque group (HTG), and a low torque group (LTG). Peak isometric (H) and concentric (H and Q) torques and rate of torque development (H) were significantly greater in the HTG group. Similarly, H-con:Q(con) (0.68 +/- 0.02 vs. 0.52 +/- 0.03) and H-rtd:Q(rtd) (0.54 +/- 0.12 vs. 0.43 +/- 0.16) were significantly greater in the HTG group than in the LTG group. There was no significant correlation between H-con:Q(con) and H-rtd:Q(rtd). It can be concluded that H-con:Q(con) and H-rtd:Q(rtd) are determined, but not fully defined, by shared putative physiological mechanisms. Thus, the physiologic and clinical significance of H-con:Q(con) and H-rtd:Q(rtd) to an athlete's individual evaluation might be different.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Physiological and Stroke Parameters to Assess Aerobic Capacity in Swimming

Purpose: To identify the speed corresponding to anaerobic threshold using the D-max method for both blood lactate and biomechanical stroke parameters determined in an incremental swimming test and to compare this information with the speed corresponding to the maximal lactate steady state (S-MLSS). Methods: Five male long-distance swimmers and 8 triathletes (N = 13; age 23.8 +/- 9.5 y, height 1.76 +/- 0.1 m, weight 71.3 +/- 9.8 kg) performed the following protocols: maximal 400-m test to determine maximal aerobic speed (S-400); 7 x 200-m incremental test to determine the speed corresponding to the D-max point on the blood lactate (S-La), stroke-rate (S-SR), stroke-length (S-SL), and stroke-index (S-SI) responses; and two to four 30-min submaximal tests to determine the S-MLSS. Results: S-LA (1.18 +/- 0.08 m/s), S-SI (1.18 +/- 0.08 m/s), S-SR (1.17 +/- 0.1 m/s), and S-SL(1.16 +/- 0.09 m/s) were not significantly different from each other or from S-MLSS (1.13 +/- 0.08 m/s). There were high correlations between S-LA, S-SI, S-SR, S-SL, and S-MLSS (r = .91, .89, .85, and .80, respectively). The typical errors of estimate for S-LA (3.2%), S-SI (3.7%), S-SR (4.1%), and S-SL (4.7%) suggest good validity of these variables to predict S-MLSS. Furthermore, all physiological and biomechanical variables were moderately to highly correlated with S-400 (r = .73-.95). Conclusions: It is possible to obtain a physiological index of aerobic capacity and performance using simple biomechanical measurements during an incremental test without performing blood lactate analyses.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq