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.

Physiological Adaptations to High-Intensity Interval and Continuous Training in Kayak Athletes.

Papandreou, A, Philippou, A, Zacharogiannis, E, and Maridaki, M. Physiological adaptations to high-intensity interval and continuous training in kayak athletes. J Strength Cond Res 34(8): 2258-2266, 2020-High-intensity interval training (HIIT) seems to be more effective than continuous training (CT) for the improvement of physical condition and sports performance. This study compared physiological adaptations with HIIT and CT in flat water kayak athletes. Twenty-four national-class kayakists were divided into 3 groups (n = 8 per group), 2 of which participated in an 8-week CT or HIIT program, whereas the third one served as control (C). An incremental maximum oxygen uptake (V[Combining Dot Above]O2max), a maximal anaerobic Wingate-type, as well as 1,000-m (T1,000 m) and 200-m (T200 m) time test were performed before and after the training period on a kayak ergometer, to determine changes in V[Combining Dot Above]O2max, peak blood lactate ([La]peak), paddling speed at V[Combining Dot Above]O2max ((Equation is included in full-text article.)), heart rate at V[Combining Dot Above]O2max (HRpeak), paddling economy speed (PEs; speed at 75% of V[Combining Dot Above]O2max), paddling speed at anaerobic ventilatory threshold (PSVT2), maximal paddling speed (PSpeak), and reduction of PSpeak (PSR). V[Combining Dot Above]O2max, [La]peak, HRpeak, and PSR did not change after the 8-week training compared with baseline in either training group (p > 0.05). However, significant changes were found in PSVT2 and T200 m (HIIT), (Equation is included in full-text article.), PEs, PSpeak, and T1,000 m (CT and HIIT) (p < 0.05-0.0001) as compared to baseline. Moreover, percent changes were different between the training groups in PEs, and between control and training groups in PSpeak and (Equation is included in full-text article.)(p < 0.05-0.01). Both training programs improved physiological and performance variables; however, HIIT resulted in significant changes of PSVT2 and T200 m and higher improvement of PEs with 15 times less training time compared with CT. Thus, HIIT seems more time-efficient than CT for improving paddling economy of kayaking performance.

Effect of a Carbohydrate-Electrolyte Solution on Fluid Balance and Performance at a Thermoneutral Environment in International-Level Fencers.

Chryssanthopoulos, C, Tsolakis, C, Bottoms, L, Toubekis, A, Zacharogiannis, E, Pafili, Z, and Maridaki, M. Effect of a carbohydrate-electrolyte solution on fluid balance and performance at a thermoneutral environment in international-level fencers. J Strength Cond Res 34(1): 152-161, 2020-The purpose of the study was to examine a possible effect of a carbohydrate-electrolyte (CHO-E) solution on fluid balance and performance in fencing at a thermoneutral environment. Sixteen fencers performed two 120-minute training sessions separated by 7-14 days under similar environmental conditions (temperature: 20.3° C and humidity: 45-47%). Each session consisted of 60-minute conditioning exercises followed by 10 bouts of 3 minutes against the same opponent with 3-minute interval between each bout. Participants ingested at regular intervals either a 6% CHO-E solution or an artificially sweetened water (PL) in a counterbalanced order. No difference was observed between conditions in the heart rate responses, perceived exertion, changes in plasma volume, urine specific gravity, number of bouts won or lost, or points for and against. Considerable variability was observed in body mass changes that revealed significant differences at the time level (i.e., pre- vs. post-exercise) (F1,15 = 9.31, p = 0.008, η = 0.38), whereas no difference was found between conditions (i.e., CHO-E vs. PL) (F1,15 = 0.43, p = 0.52, η = 0.03) and conditions × time interaction (F1,15 = 3.57, p = 0.078, η = 0.19). Fluid loss was not significantly different between conditions (p = 0.08, d = 0.47). The blood glucose level was higher (p < 0.01) after exercise in CHO-E, whereas the blood lactate level was similar between conditions. In conclusion, the CHO-E solution was as effective as the artificially sweetened water in terms of fluid balance and fencing performance at a thermoneutral environment. Because of large individual variability, fencers should monitor their fluid intake and body fluid loss in training and competition.

Sprint mechanical differences at maximal running speed: Effects of performance level.

As the effect of performance level on sprinting mechanics has not been fully studied, we examined mechanical differences at maximal running speed (MRS) over a straight-line 35 m sprint amongst sprinters of different performance levels. Fifty male track and field sprinters, divided in Slow, Medium and Fast groups (MRS: 7.67 ± 0.27 m∙s-1, 8.44 ± 0.22 m∙s-1, and 9.37 ± 0.41 m∙s-1, respectively) were tested. A high-speed camera (250 Hz) recorded a full stride in the sagittal plane at 30-35 m. MRS was higher (p < 0.05) in Fast vs. Medium (+11.0%) and Slow (+22.1%) as well as in Medium vs. Slow (+10.0%). Twelve, eight and seven out of 21 variables significantly distinguished Fast from Slow, Fast from Medium and Medium from Slow sprinters, respectively. Propulsive phase was significantly shorter in Fast vs. Medium (-17.5%) and Slow (-29.4%) as well as in Medium vs. Slow (-14.4%). Fast sprinters had significantly higher vertical and leg stiffness values than Medium (+44.1% and +18.1%, respectively) and Slow (+25.4% and +22.0%, respectively). MRS at 30-35 m increased with performance level during a 35-m sprint and was achieved through shorter contact time, longer step length, faster step rate, and higher vertical and leg stiffness.

Carbohydrate mouth rinse does not affect performance during a 60-min running race in women.

This study examined the effect of carbohydrate mouth rinsing on endurance running performance in women. Fifteen female recreational endurance runners, who used no oral contraceptives, ran two races of 1-h duration on an indoor track (216-m length) at 18:00 h after an 8-h fast with a 7-days interval between races, corresponding to the 3rd-10th day of each premenopausal runner's menstrual cycle, or any day for the postmenopausal runners. In a double-blind random order, participants rinsed their mouth with 25 ml of either a 6.4% carbohydrate (RCHO) or a placebo solution (RP). No fluid was ingested during exercise. Serum 17ß-Εstradiol (P = 0.59) and Progesterone (P = 0.35) did not differ between treatments. There was no difference in 1-hour running performance (RCHO: 10,621.88 ± 205.98 m vs. RP: 10,454.00 ± 206.64 m; t = 1.784, P = 0.096). Furthermore, the mean percentage effect (±99%CI) of RCHO relative to RP, 1.67% (-1.1% to 4.4%), and Cohen's effect size (d = 0.21) support a trivial outcome of RCHO for total distance covered. In conclusion, carbohydrate mouth rinsing did not improve 60-min track running performance in female recreational runners competing in a low ovarian hormone condition, after an 8-h fast and when no fluid was ingested during exercise.

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.

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.

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.

Influence of type of muscle contraction and gender on postactivation potentiation of upper and lower limb explosive performance in elite fencers.

The purpose of this study was to evaluate the postactivation potentiation (PAP) effect of isometric and plyometric contractions on explosive performance of the upper and the lower limbs in male and female elite athletes. Thirteen male and ten female international level fencers performed four protocols of either isometric (3 sets of 3 sec) or plyometric (3 sets of 5 repetitions) bench and leg press, in a within subject randomized design. Before and immediately after the PAP treatment and following 4, 8, 12 min, explosive performance was measured by performing a countermovement jump (CMJ) or a bench press throw. Statistical analysis revealed significant time effect for peak leg power during the CMJ (p < 0.001) only for men, with values after the isometric PAP treatment being lower than baseline at the 8 and 12 min time points (by 7.5% (CI95% = 3.9-11.2%) and 8.7% (CI95% = 6.0-11.5%, respectively), while after the plyometric PAP treatment peak leg power remained unchanged. A significant negative correlation was found between leg strength (as expressed by 1-RM leg press performance) and the change in peak leg power between baseline and after 12 min of recovery only in male fencers (r = -0.55, p < 0.05), suggesting that stronger individuals may show a greater decrease in peak leg power. Based on the above results we conclude that lower body power performance in international level fencers may be negatively affected after isometric contractions and thus they should be advised against using isometric exercises to induce PAP with the protocol prescribed in the present study. Furthermore, gender and strength level must be considered in the practical application of PAP. Key pointsSignificantly lower values for peak power of the legs were noted in men at 8 and 12 min of recovery in response to the PAP protocol used in this studyThere is some evidence to suggest that stronger individuals may have a greater and longer lasting fatigue that may actually result in a decrease rather than increase of performance after a PAP protocolFencers should be advised to avoid the use of isometric exercises in warm-up routines to augment explosive performance.

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.

Effect of acupuncture in physiological parameters and endurance running performance.

BACKGROUND: Few studies have examined the effect of acupuncture (AC) treatment in aerobic capacity and endurance performance in healthy adults. Thus, the aim of the present study was to evaluate the effects of AC on selected physiological parameters and 3 km running performance. METHODS: Twenty-four healthy subjects with low to moderate aerobic capacity participated in the study and randomly assigned in two groups: AC group (ACG - N.=14) and control group (CG - N.=10). The subjects completed an incremental test to exhaustion and a 3 km race on a treadmill to evaluate their physiological responses and endurance running performance respectively, prior and after 4 weeks (8 sessions, twice a week) of acupuncture treatment. RESULTS: AC treatment had a significant main effect in T3km [F(1, 21)=7.173, P=0.014, partial η2=0.255], as well as in VT [F(1, 21)=8.476, P=0.008, partial η2=0.288] and HRmax@3km [F(1, 21)=4.930, P=0.038, partial η2=0.190], after controlling for the effect of the pre-test, while no other significant main effects were detected. CONCLUSIONS: Healthy physically active adults significantly improved their endurance running performance after 4 weeks of AC treatment. This is mainly due to the enhancement of the speed corresponding with VT, comparing with their baseline values.

Contribution of select physiological variables to sprint triathlon performance.

BACKGROUND: The purpose of this study was to examine the relationship between select physiological variables and sprint triathlon performance. METHODS: Moderately trained male triathletes (N.=15) performed two graded maximal exercise tests, on a cycle ergometer and a treadmill. Anaerobic capacity was evaluated, on a cycle ergometer and a treadmill. Within two weeks before or after the testing, all triathletes participated in a sprint triathlon race (750 m sea swim, 20 km cycle, 5 km run). RESULTS: The results showed that significant correlations exist between VO2max during cycling (r=-0.811, P<0.05) or running (r=-0.757, P<0.05) and overall triathlon performance. Stepwise multiple linear regression analysis, with triathlon performance as the dependent variable and the physiological measures during running as the independent variables, showed that VO2max (mL.min-1.kg-1), Time_CF, CHO_rate @ VT and % body fat yielded the best prediction of performance (R2=0,912). When only the physiological variables from cycling were included into the model, the results showed that VO2max (mL.min-1), VO2max (mL.min-1.kg-1) and PFmax (rpm) explained 88% of the variation in sprint triathlon performance. CONCLUSIONS: Our data indicate that overall race time for moderately trained triathletes, competing over the sprint distance can be accurately predicted from maximal laboratory tests.

The effect of pacing strategy on physiological, kinetic and performance variables during simulated rowing ergometer.

BACKGROUND: This study compared the effects of self-selected (SSP), negative (NPS), and even pacing strategy (EPS) on performance time, and kinetic and physiological variables in overall 2-km rowing and in first and second 1 km. METHODS: Fifteen male rowers (15.37±1.34 years) realized four tests: an incremental test on a rowing ergometer to determine their VO2peak and three experimental 2-km rowing race, where first 1 km was manipulated. From SSP a negative pacing strategy, 4% slower than the mean velocity of SSP, and an even pacing strategy (EPS) with mean velocity of SSP, were developed. RESULTS: High stroke rate and better performance time were observed in SSP. Fstr and Fpeak decreased, whereas performance time increased, in SSP and EPS from first to second 1 km. However, performance time, stroke rate and Pst in NPS presented better values (P=0.001) with the exception of decreased stroke length (P=0.03). There was an increase in physiological responses in all pacing strategies from first to second 1 km (P=0.001). Performance time, stroke rate and Fstr were better in SSP and EPS compared to NPS in first 1 km (P=0.001). VE, VE/VO2, VCO2 were better in SSP and EPS compared to NPS (P=0.001) in both first and second 1 km. Stroke length was smaller in SSP compared to NPS and EPS in second 1 km (P=0.001). CONCLUSIONS: SSP (parabolic-shaped profile) allowed rowers to cover the 2-km distance at higher stroke rate and in shorter performance time compared to negative and even pacing strategies presenting same physiological responses.

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.