Physiological Responses and Swimming-Performance Changes Induced by Altering the Sequence of Training Sets.

PURPOSE: Interval-training sets may be applied in a different sequence within a swimming training session. The aim of this study was to investigate the effect of different set sequences on performance and physiological responses in a training session. METHODS: Twelve highly trained male swimmers performed 4 sessions in randomized order. Each session included a different combination of 2 training sets: set A-set C, set C-set A, set B-set C, or set C-set B. Set A consisted of 8 × 200 m at speed corresponding to lactate threshold (30-s recovery), set B included 8 × 100 m at maximum aerobic speed (30-s recovery), and set C included 4 × 50-m all-out swimming (2-min recovery). Performance and physiological responses (lactate concentration, pH, base excess, bicarbonate, heart rate, and heart-rate variability) were measured. RESULTS: Performance in each set was similar between sessions irrespective of set sequence. Blood lactate, heart rate, and acid-base responses during set C were similar in all sessions, but blood lactate was higher in sets A and B during C-A and C-B sessions (P = .01). The overall blood lactate and acid-base response was higher in C-A and C-B sessions compared with A-C and B-C sessions, respectively (P = .01). Heart-rate variability in each set, separately as well as the overall session effect, did not differ and was thus independent to the set sequence applied. CONCLUSIONS: Training sessions including all-out swimming as a first set increase the magnitude of metabolic responses to the subsequent aerobic-dominated training set.

Effects of Training Sets Sequence on Swimming Performance, Training Load and Physiological Responses.

The study examined the effect of set sequence on performance and physiological responses in a training session and in each set separately. Twelve male swimmers performed four sessions in a randomized order, including a combination of two training sets: (i) set A-set C, (ii) set C-set A, (iii) set B-set C, (iv) set C-set B. Set A consisted of 8 × 200 m at a speed corresponding to lactate threshold (30 s recovery), set B included 8 × 100 m at the maximal aerobic speed (30 s recovery), set C included 8 × 50 m sprints at 95% of the maximum 50 m speed (30 s recovery). Speed, blood lactate, pH, base excess, bicarbonate and heart rate variability (HRV) were measured. Speed in each set was similar between sessions irrespective of set sequence (p > 0.05). Physiological responses during sets A and C were similar in all sessions (p > 0.05). In set B, when applied after set C, the metabolic response increased, and HRV decreased (p < 0.05). Overall, session biochemical disturbance was higher when set C was applied before sets A and B (p < 0.05). The magnitude of metabolic and HRV responses in a set conducted at maximal aerobic speed, but not at lactate threshold intensity, is increased when applied after sprint intervals.

Recreational Runners Gain Physiological and Biomechanical Benefits From Super Shoes at Marathon Paces.

PURPOSE: Advanced footwear technology is prevalent in distance running, with research focusing on these "super shoes" in competitive athletes, with less understanding of their value for slower runners. The aim of this study was to compare physiological and biomechanical variables between a model of super shoes (Saucony Endorphin Speed 2) and regular running shoes (Saucony Cohesion 13) in recreational athletes. METHODS: We measured peak oxygen uptake (VO2peak) in 10 runners before testing each subject 4 times in a randomly ordered crossover design (ie, Endorphin shoe or Cohesion shoe, running at 65% or 80% of velocity at VO2peak [vVO2peak]). We recorded video data using a high-speed camera (300 Hz) to calculate vertical and leg stiffnesses. RESULTS: 65% vVO2peak was equivalent to a speed of 9.4 km·h-1 (0.4), whereas 80% vVO2peak was equivalent to 11.5 km·h-1 (0.5). Two-way mixed-design analysis of variance showed that oxygen consumption in the Endorphin shoe was 3.9% lower than in the Cohesion shoe at 65% vVO2peak, with an interaction between shoes and speed (P = .020) meaning an increased difference of 5.0% at 80% vVO2peak. There were small increases in vertical and leg stiffnesses in the Endorphin shoes (P < .001); the Endorphin shoe condition also showed trivial to moderate differences in step length, step rate, contact time, and flight time (P < .001). CONCLUSIONS: There was a physiological benefit to running in the super shoes even at the slower speed. There were also spatiotemporal and global stiffness improvements indicating that recreational runners benefit from wearing super shoes.

Kinematic and Temporal Differences Between World-Class Men's and Women's Hurdling Techniques.

This study aimed to compare joint kinematics and center of mass parameters throughout hurdle clearance between world-class men and women sprint hurdlers, who were competing in a World Championships final. This was the first study to present time-series kinematic data around hurdle clearance, and given the technical ability of the athletes analyzed, it can be used as a template when analyzing the technique of other athletes in similar competitions and training. Video data were collected of the 16 finalists at the 2017 IAAF World Championships using four high-speed cameras (150 Hz). Video files were continuously digitized manually from touchdown before hurdle clearance to toe-off after landing around the sixth hurdle for men and the fifth hurdle for women, and sex-based comparisons were made at key discrete time points using independent t-tests, and throughout the entire hurdle phase using statistical parametric mapping. When calculated relative to hurdle height, the women's center of mass height was significantly greater than the men's throughout the full analyzed sequence (p < 0.001). Men also displayed more hip flexion in the lead leg at take-off before hurdle clearance (p = 0.029) as well as a more extended knee joint at intervals during flight and upon landing (p ≤ 0.037). Women completed the hurdle phase in a significantly shorter time than men (~11% difference, p < 0.001). Finally, women seemed to be more efficient by maintaining and even exceeding their entry velocity for the first 40% of the hurdle phase. These results show a lower technical demand for the women to successfully negotiate hurdle clearance, thus providing further evidence to support the argument that the women's hurdle height is too low for their performance capabilities and should be raised in senior competition.

Kinematics of the Final Approach and Take-Off Phases in World-Class Men and Women Pole Vaulters.

The pole vault is a highly technical event where the athletes must successfully convert horizontal velocity during the run-up to vertical velocity at take-off. The aim of this study was to compare the kinematics of men's and women's world-class pole vaulting. Video data were collected of the best clearances by 14 men and 11 women at the 2018 IAAF World Indoor Championships using three high-speed cameras (200 Hz). Running velocity, step lengths, step times, and pole angles were measured during the run-up; during take-off, distance from the plant box, angle and velocity of take-off, and relative positions of the foot and hands were measured. Men achieved greater clearance heights with faster run-ups, faster take-off velocities and higher hand grip positions (all p < 0.001), with each of the last three steps longer for men when expressed as absolute values (all p < 0.001), but not when expressed relative to stature. There were no differences in run-up pole angles, step times, take-off angle, take-off contact time or time from pole plant to take-off. Women differed in their approach and take-off for characteristics affected by stature and strength, such as fewer run-up steps, shorter take-off distances, and lower grip heights. These lower grips result from a shorter, lighter pole, and this disadvantage was greater than slower run-up velocities. Coaches should therefore note that sex-based differences occur in the pole vault that result from anthropometric differences, but which do not negate the adoption of similar technical models of vaulting.

Development and Maintenance of Sprint Training Adaptations: An Uphill-Downhill Study.

ABSTRACT: Bissas, A, Paradisis, GP, Nicholson, G, Walker, J, Hanley, B, Havenetidis, K, and Cooke, CB. Development and maintenance of sprint training adaptations: an uphill-downhill study. J Strength Cond Res 36(1): 90-98, 2022-We examined the development of performance adaptations resulting from an uphill-downhill training program and monitored the decline of adaptations during detraining. Twenty-eight men were randomly assigned to 1 of 2 sprint training groups who trained 3 times per week for 6 weeks and a control group (C). The uphill-downhill group (U+D) trained on an 80-m platform with 3° slopes, whereas the horizontal (H) group trained on flat track. Subjects were tested for maximal running speed (MRS), associated kinematics, and leg strength before and after training, with U+D subjects also tested after weeks 2 and 4 of training, and after a 3-week detraining period. The U+D group increased their MRS by 3.7% (from 8.75 ± 0.72 to 9.07 ± 0.64 m·s-1, p < 0.05), their stride rate by 3.1% (from 4.21 ± 0.21 to 4.34 ± 0.18 Hz, p < 0.05), and their knee extensors' maximum isometric force by 21% (from 2,242 ± 489 to 2,712 ± 498 N, p < 0.05) after training. The time course of changes showed declines for weeks 1-4 (1.4-5.1%), but an ascending trend of improvement compensated all losses by the end of week 6 (p < 0.05). During detraining, no decreases occurred. No changes were observed for the H and C groups. The minimum period to produce positive effects was 6 weeks, with a very good standard of performance maintained 3 weeks after training. U+D training will prove useful for all athletes requiring fast adaptations, and it can fit into training mesocycles because of its low time demands.

Asymmetry in sprinting: An insight into sub-10 and sub-11 s men and women sprinters.

We assessed sprint mechanical asymmetry in world-class competitors and evaluated whether inter-limb sex-based differences in sprinting mechanics exist. The eight finalists in the men's and women's 100 m events at the 2017 IAAF World Championships were studied. Five high-speed cameras (150 Hz) were used to capture two consecutive steps of the whole body between 47.0 m and 55.5 m from the start, while four additional cameras (250 Hz) focussed on the lower extremities. A total of 33 spatio-temporal, touchdown and toe-off joint angles, and horizontal and vertical foot velocity parameters were extracted through three-dimensional analysis. Group mean asymmetry scores were assessed using the symmetry angle (SA) where scores of 0% and 100% represent perfect symmetry and perfect asymmetry, respectively. Although considered generally low (SA <3% for 22 out of 33 parameters), the magnitude of mechanical asymmetry varied widely between sprinters of the same sex. However, there was no mean SA scores difference between men and women for any stride mechanical parameters (all p ≥ 0.064). Asymmetry scores were inconsistent between parameters and phases (touchdown vs toe-off instants), and sprinting mechanics were generally not related to asymmetry magnitudes. In summary, low to moderate asymmetry is a natural phenomenon in elite sprinting. Asymmetry was inconsistent between parameters and competitors during near maximum velocity running, yet mean values for a given parameter generally did not differ between sexes. Sprinters' performances were not related to their SA scores.

Influence of lower limb dominance on mechanical asymmetries during high-speed treadmill running.

We determine whether mechanical asymmetries differ between dominant and non-dominant legs at fast treadmill speed. Stride temporal variables, derived from high-speed camera recordings, allowed to estimate leg and vertical stiffness through the sine-wave method in 31 uninjured males during treadmill running at 6.67 m.s-1. Lower limb dominance was determined by the triple-jump test. The asymmetry was expressed as dominant-non-dominant and indexed by the absolute asymmetry index (ASI). The lowest and highest mean ASI values were detected for contact time (1.69%) and flight time (5.66%), respectively; ASI values for spring-mass characteristics (2.6% ≤ leg and vertical stiffness, peak vertical force, change in vertical leg length and centre of mass vertical displacement ≤ 4.7%) were within this range. Inter-subject variability in ASI varied substantially among the seven analysed variables with larger and smaller range of variability in ASI found for flight time (0-16.56%) and contact time (0-3.47%), respectively. Because the magnitude of group mean ASI appears inconsistent among stride temporal and spring-mass characteristics, different biomechanical variables should not be used interchangeably to assess laterality effects at fast treadmill speed. The widespread ASI range also indicates that using a 'fixed cut-off' threshold is an arbitrary approach.

Acute Effects of Whole-Body Vibration Warm-up on Leg and Vertical Stiffness During Running.

ABSTRACT: Paradisis, GP, Pappas, P, Dallas, G, Zacharogiannis, E, Rossi, J, and Lapole, T. Acute effects of whole-body vibration warm-up on leg and vertical stiffness during running. J Strength Cond Res 35(9): 2433-2438, 2021-Although whole-body vibration (WBV) has been suggested as a suitable and efficient alternative to the classic warm-up routines, it is still unknown how this may impact running mechanics. Therefore, the aim of this study was to investigate the effect of a WBV warm-up procedure on lower-limb stiffness and other spatiotemporal variables during running at submaximal speed. Twenty-two males performed 30-second running bouts at 4.44 m·s-1 on a treadmill before and after a WBV and control warm-up protocols. The WBV protocol (vibration frequency: 50 Hz, peak-to-peak displacement: 4 mm) consisted of 10 sets of 30-second dynamic squatting exercises with 30-second rest periods within sets. Leg and vertical stiffness values were calculated using the spring mass model. The results indicated significant increases only after the WBV protocol for leg stiffness (3.4%), maximal ground reaction force (1.9%), and flight time (4.7%). Consequently, the WBV warm-up protocol produced a change in running mechanics, suggesting a shift toward a more aerial pattern. The functional significance of such WBV-induced changes needs further investigation to clearly determine whether it may influence running economy and peak velocity.

Biomechanics of World-Class Men and Women Hurdlers.

The sprint hurdle events require athletes to cross ten hurdles between the start and finish line. The height of the hurdles, and the distances between them, differ for men and women, possibly resulting in technical differences. The aim of this study was to provide a kinematic comparison of in-competition hurdle technique for world-class men and women hurdlers. Video data were collected for the 16 finalists in the 100 m and 110 m hurdles events at the 2017 IAAF World Championships using four high-speed cameras (150 Hz), focusing on the sixth hurdle for the men and fifth for the women. Center of mass (CM) position, joint angles, step lengths and clearance times were compared between sexes at key events before, during and after hurdle clearance. The hurdle height was ~7% higher for men when calculated as a proportion of stature (p < 0.001). This discrepancy in relative hurdle height provided women with a kinematic and mechanical advantage over men as they took off farther from the hurdle (relative to hurdle height) (p < 0.001), leading to a lower and more efficient flight parabola. Women were also able to maintain longer relative step lengths after hurdle clearance and showed minimal vertical oscillation of the CM in the stance phases before and after the hurdle compared with men. The lower relative hurdle heights in the women's event provide a less demanding task, and thus these findings present preliminary evidence to those coaches who advocate revising the women's hurdle heights in competition.

Kinematic factors associated with start performance in World-class male sprinters.

The aim was to investigate the kinematic factors associated with successful performance in the initial acceleration phase of a sprint in the best male athletes in the World at the 2018 World Indoor Athletics Championships. High speed video (150 Hz) was captured for eight sprinters in the men's 60 m final. Spatio-temporal and joint kinematic variables were calculated from the set position to the end of the first ground contact post-block exit (GC1). Normalised average horizontal external power (NAHEP) defined performance and was the dependent variable for a series of regression analyses. Clear relationships were found between GC1 NAHEP and 10-m time, 60-m time, change in velocity, acceleration and contact time in the first ground contact (r = -0.74, -0.64, 0.96, 0.91 and -0.56, respectively). Stepwise multiple linear regression of joint kinematic variables in the first ground contact revealed that trunk angle at take-off and thigh separation angle at take-off explained nearly 90% of variation in GC1 NAHEP (R2 = 0.89). The athletes' projection at take-off with a forward leaning trunk and large thigh separation is characteristic therefore of excellent initial acceleration performance and this will be a good visual guide for technical coaching instruction. This was the first study of its kind to adopt such a research design in a World-class sample in a representative environment. Future studies that combine detailed kinematic and kinetic data capture and analysis in such a setting will add further insight to the findings of this investigation.

Energy expenditure during a Vinyasa yoga session.

BACKGROUND: Vinyasa yoga has been recently promoted as one of the most popular mindful exercises to improve overall health, including body weight management. The purpose of this study was to determine the metabolic response of 24 moderately trained individuals during a 90-min group Vinyasa yoga routine. METHODS: Heart rate (HR) time course of 12 males and 12 females (age: 39±7.33 years) was recorded during two group Vinyasa yoga sessions consisted of four sections (warm-up, high-intensity Surya Namaskar (HSN), no Surya Namaskar postures, and cool-down). Maximal oxygen uptake (V̇O2peak) and maximum HR had been estimated earlier after a maximal treadmill test. V̇O2 during Vinyasa yoga sessions was estimated from individual regression equations using the relationship of V̇O2 and HR values derived from V̇O2peak test, while the metabolic rate (kcal/min) was calculated from the relationship of HR and kcal/min. Total session energy consumption was the average value of the two yoga sessions. RESULTS: The 2 (gender) × 4 (sections) mixed ANOVA revealed no significant interaction between the two factors (P=0.101) for the mean metabolic rate (7.1±2.6 kcal/min). Mean metabolic rate thought was higher (P=0.015) in males compared to females at each section. Also, significant differences were found among the four Vinyasa yoga sections (P<0.001) in the rate of energy expenditure, with HSN presenting the highest mean values (P<0.05). CONCLUSIONS: It seems that systematic participation in Vinyasa yoga may effectively improve cardiorespiratory fitness and promote body weight loss, as an alternative method to traditional aerobic exercise.

The effect of four weeks of plyometric training on reactive strength index and leg stiffness is sport dependent.

BACKGROUND: Plyometric exercises are often used to develop lower limb strength and performance-related biomechanics such as leg stiffness. However, the effectiveness of plyometric training may depend on participants' own training and performance demands. The purpose of this study was to examine the effect of plyometric training on Reactive Strength Index (RSI) and leg stiffness (Kleg) on young athletes of different sports. METHODS: Forty eight female athletes (25 Taekwondo (TKD) and 23 rhythmic gymnastics (RG), mean±SD: age: 8.94±2.50 years; mass: 29.73±7.69 kg; height: 138.84±11.90 cm; training experience: 4.62±2.37 years) participated in this study. Participants were randomly assigned to experimental (PT, N.=24) and control (CG, N.=24) groups. The PT group followed a twice-weekly plyometric training program for 4 weeks. Plyometric drills lasted approximately 5-10 s, and at least 90 s rest was allowed after each set. To examine RSI, participants performed trials of five maximal CMJs. Submaximal hopping (20 hops) was performed in order to examine leg stiffness. RESULTS: Significant interaction effect was found for RSI and the post hoc analysis showed that RSI significantly increased by 35% (P=0.017) in RG athletes, whereas a significantly reduction by 28% (P=0.004) was revealed in TKD athletes. The interaction effect between time and group was statistically significant for Kleg (P<0.05) with Kleg significantly increasing by 31% (P=0.008) in TKD athletes, but remaining unchanged (P>0.05) in RG athletes. CONCLUSIONS: The results showed that the effect of a 4-week plyometric training program on RSI and leg stiffness is sport dependent. Further, the applied plyometric program was effective in reducing ground contact time and therefore increasing leg stiffness.

Physiological Responses of Continuous and Intermittent Swimming at Critical Speed and Maximum Lactate Steady State in Children and Adolescent Swimmers.

BACKGROUND: The purpose of this study was to compare physiological responses during continuous and intermittent swimming at intensity corresponding to critical speed (CS: slope of the distance vs. time relationship using 200 and 400-m tests) with maximal lactate steady state (MLSS) in children and adolescents. METHODS: CS and the speed corresponding to MLSS (sMLSS) were calculated in ten male children (11.5 ± 0.4 years) and ten adolescents (15.8 ± 0.7 years). Blood lactate concentration (BL), oxygen uptake ( V · O2), and heart rate (HR) at sMLSS were compared to intermittent (10 × 200-m) and continuous swimming corresponding to CS. RESULTS: CS was similar to sMLSS in children (1.092 ± 0.071 vs. 1.083 ± 0.065 m·s-1; p = 0.12) and adolescents (1.315 ± 0.068 vs. 1.297 ± 0.056 m·s-1; p = 0.12). However, not all swimmers were able to complete 30 min at CS and BL was higher at the end of continuous swimming at CS compared to sMLSS (children: CS: 4.0 ± 1.8, sMLSS: 3.4 ± 1.5; adolescents: CS: 4.5 ± 2.3, sMLSS: 3.1 ± 0.8 mmol·L-1; p < 0.05). V · O2 and HR in continuous swimming at CS were not different compared to sMLSS (p > 0.05). BL, V · O2 and HR in 10 × 200-m were similar to sMLSS and no different between groups. CONCLUSION: Intermittent swimming at CS presents physiological responses similar to sMLSS. Metabolic responses of continuous swimming at CS may not correspond to MLSS in some children and adolescent swimmers.

Acute Effects of Stretching on Leg and Vertical Stiffness During Treadmill Running.

Pappas, PT, Paradisis, GP, Exell, TA, Smirniotou, AS, Tsolakis, CK, and Arampatzis, A. Acute effects of stretching on leg and vertical stiffness during treadmill running. J Strength Cond Res 31(12): 3417-3424, 2017-The implementation of static (SS) and dynamic (DS) stretching during warm-up routines produces significant changes in biological and functional properties of the human musculoskeletal system. These properties could affect the leg and vertical stiffness characteristics that are considered important factors for the success of athletic activities. The aim of this study was to investigate the influence of SS and DS on selected kinematic variables, and leg and vertical stiffness during treadmill running. Fourteen men (age: 22.58 ± 1.05 years, height: 1.77 ± 0.05 m, body mass: 72.74 ± 10.04 kg) performed 30-second running bouts at 4.44 m·s, under 3 different stretching conditions (SS, DS, and no stretching). The total duration in each stretching condition was 6 minutes, and each of the 4 muscle groups was stretched for 40 seconds. Leg and vertical stiffness values were calculated using the "sine wave" method, with no significant differences in stiffness found between stretching conditions. After DS, vertical ground reaction force increased by 1.7% (p < 0.05), which resulted in significant (p < 0.05) increases in flight time (5.8%), step length (2.2%), and vertical displacement of the center of mass (4.5%) and a decrease in step rate (2.2%). Practical durations of SS and DS stretching did not influence leg or vertical stiffness during treadmill running. However, DS seems to result in a small increase in lower-limb force production which may influence running mechanics.

Step characteristic interaction and asymmetry during the approach phase in long jump.

The aim of this study was to investigate the relative influence of step length (SL) and step frequency (SF) on step velocity (SV) during the approach run of high-level long jumpers and to quantify the asymmetry of these step characteristics. Spatiotemporal data of the approach run were collected during national competition from 10 long jumpers (age 26.2 ± 4.1 years, height 1.84 ± 0.06 m, mass 72.77 ± 3.23 kg, personal best performance 7.96 ± 0.30 m). Analyses were conducted for total approach, early approach and late approach. For the total approach 4/10 athletes were SF reliant and 6/10 athletes favoured neither characteristic. At the early approach, 3/10 athletes were SF reliant and 7/10 athletes favoured neither. During late approach 2/10 athletes demonstrated SL reliance, 7/10 athletes were SF reliant and 1/10 athletes favoured neither. Four athletes displayed significant asymmetry for SL and three for SF. However, no athletes demonstrated significant asymmetry for SV indicating that the asymmetrical demands of take-off do not have a marked influence on step characteristic asymmetry, probably due to the constraints of the event. Consideration should be given to the potentially conflicting demands between limbs for individual athletes.

Variability of performance during a 60-min running race.

The aim of the present study was to examine the variability of 1-h running performance outside the laboratory, under conditions simulating those of a real competitive event. Twenty-three male recreational runners performed on 3 occasions a 60-min simulated running race attempting to cover as long distance as possible. The races took place in an indoor track, in order to ensure stable environmental conditions. There was no difference in the distance covered between races (12,546.3 ± 217 m, 12,576 ± 219.1 m, 12,638.7 ± 225.3 m for the 1st, 2nd and 3rd races, respectively (mean ± S(X), F(2, 44) = 1.168, P = 0.32). The coefficient of variation for all participants was 1.5 ± 0.2 (range: 0.2-3.00). Multiple regression analysis indicated that 83% of the variability in best performance was predicted by determining the speed at the peak volume of oxygen uptake and body mass. In conclusion, performance during 1-h simulated running race in an indoor track was highly reproducible. The present study can be used as low-cost, time-efficient and ecologically valid tool, which could test simultaneously numerous runners' performance under conditions similar to real competitive events.

Multi-Stage 20-m Shuttle Run Fitness Test, Maximal Oxygen Uptake and Velocity at Maximal Oxygen Uptake.

The multi-stage 20-m shuttle run fitness test (20mMSFT) is a popular field test which is widely used to measure aerobic fitness by predicting maximum oxygen uptake (VO2max) and performance. However, the velocity at which VO2max occurs (vVO2max) is a better indicator of performance than VO2max, and can be used to explain inter-individual differences in performance that VO2max cannot. It has been reported as a better predictor for running performance and it can be used to monitor athletes' training for predicting optimal training intensity. This study investigated the validity and suitability of predicting VO2max and vVO2max of adult subjects on the basis of the performance of the 20mMST. Forty eight (25 male and 23 female) physical education students performed, in random order, a laboratory based continuous horizontal treadmill test to determine VO2max, vVO2max and a 20mMST, with an interval of 3 days between each test. The results revealed significant correlations between the number of shuttles in the 20mMSFT and directly determined VO2max (r = 0.87, p<0.05) and vVO2max (r = 0.93, p<0.05). The equation for prediction of VO2max was y = 0.0276x + 27.504, whereas for vVO2max it was y = 0.0937x + 6.890. It can be concluded that the 20mMSFT can accurately predict VO2max and vVO2max and this field test can provide useful information regarding aerobic fitness of adults. The predicted vVO2max can be used in monitoring athletes, especially in determining optimal training intensity.

Effects of static and dynamic stretching on sprint and jump performance in boys and girls.

The aim of this study was to investigate the acute effects of static (SS) and dynamic stretching (DS) on explosive power, flexibility, and sprinting ability of adolescent boys and girls and to report possible gender interactions. Forty-seven active adolescent boys and girls were randomly tested after SS and DS of 40 seconds on quadriceps, hamstrings, hip extensors, and plantar flexors; no stretching was performed at the control condition. Pretreatment and posttreatment tests examined the effects of stretching on 20-m sprint run (20 m), countermovement jump (CMJ) height, and sit and reach flexibility test. In terms of performance, SS hindered 20 m and CMJ in boys and girls by 2.5 and 6.3%, respectively. Dynamic stretching had no effect on 20 m in boys and girls but impaired CMJ by 2.2%. In terms of flexibility, both SS and DS improved performance with SS being more beneficial (12.1%) compared with DS (6.5%). No gender interaction was found. It can therefore be concluded that SS significantly negates sprinting performance and explosive power in adolescent boys and girls, whereas DS deteriorates explosive power and has no effect on sprinting performance. This diversity of effects denotes that the mode of stretching used in adolescent boys and girls should be task specific.

Combined uphill and downhill sprint running training is more efficacious than horizontal.

PURPOSE: This study examined the effects of sprint running training on sloping surfaces (3 degrees) on selected kinematic and physiological variables. METHODS: Fifty-four sport and physical education students were randomly allocated to one of two training groups (combined uphill-downhill [U+D] and horizontal (H)) and a control group (C). Pre- and posttraining tests were performed to examine the effects of 8 wk of training on the maximum running speed (MRS), step rate, step length, step time, contact time, eccentric and concentric phase of contact time (EP, CP), flight time, selected posture characteristics of the step cycle, and 6-s maximal cycle sprint test. RESULTS: MRS, step rate, contact time, and step time were improved significantly in a 35-m sprint test for the U+D group (P<.01) after training by 4.3%, 4.3%, -5.1%, and -3.9% respectively, whereas the H group showed smaller improvements, (1.7% (P<.05), 1.2% (P<.01), 1.7% (P<.01), and 1.2% (P<.01) respectively). There were no significant changes in the C group. The posture characteristics and the peak anaerobic power (AWT) performance did not change with training in any of the groups. CONCLUSION: The U+D training method was significantly more effective in improving MRS and the kinematic characteristics of sprint running than a traditional horizontal training method.