Perceptual and physiological responses to recovery from a maximal 30-second sprint

ABSTRACT: Glaister, M, Pattison, JR, Dancy, B, and McInnes, G. Perceptual and physiological responses to recovery from a maximal 30-second sprint. J Strength Cond Res 26(10): 2850-2857, 2012-The aims of this study were to evaluate perceptions of postexercise recovery and to compare patterns of perceived recovery with those of several potential mediating physiological variables. Seventeen well-trained men (age: 22 ± 4 years; height: 1.83 ± 0.05 m; body mass: 78.9 ± 7.6 kg; and body fat: 11.1 ± 2.2%) completed 10 sprint trials on an electromagnetically braked cycle ergometer. Trial 1 evaluated peak power via a 5-second sprint. The remaining trials evaluated (a) the recovery of peak power after a maximal 30-second sprint using rest intervals of 5, 10, 20, 40, 80, and 160 seconds; (b) perceived recovery via visual analog scales; and (c) physiological responses during recovery. The time point in recovery at which individuals perceived they had fully recovered was 163.3 ± 57.5 seconds. Power output at that same time point was 83.6 ± 5.2% of peak power. There were no significant differences between perceived recovery and the recovery processes of V[Combining Dot Above]O2 or minute ventilation (VE). Despite differences in the time courses of perceived recovery and the recovery of power output, individuals were able to closely predict full recovery without the need for external timepieces. Moreover, the time course of perceived recovery is similar to that of V[Combining Dot Above]O2 and VE.     

The effects of ionized and nonionized compression garments on sprint and endurance cycling

ABSTRACT: Burden, RJ and Glaister, M. The effects of ionized and nonionized compression garments on sprint and endurance cycling. J Strength Cond Res 26(10): 2837-2843, 2012-The aim of this study was to examine the effects of ionized and nonionized compression tights on sprint and endurance cycling performance. Using a randomized, blind, crossover design, 10 well-trained male athletes (age: 34.6 ± 6.8 years, height: 1.80 ± 0.05 m, body mass: 82.2 ± 10.4 kg, V[Combining Dot Above]O2max: 50.86 ± 6.81 ml·kg·min) performed 3 sprint trials (30-second sprint at 150% of the power output required to elicit V[Combining Dot Above]O2max [pV[Combining Dot Above]O2max] + 3 minutes recovery at 40% pV[Combining Dot Above]O2max + 30-second Wingate test + 3 minutes recovery at 40% pV[Combining Dot Above]O2max) and 3 endurance trials (30 minutes at 60% pV[Combining Dot Above]O2max + 5 minutes stationary recovery + 10-km time trial) wearing nonionized compression tights, ionized compression tights, or standard running tights (control). There was no significant effect of garment type on key Wingate measures of peak power (grand mean: 1,164 ± 219 W, p = 0.812), mean power (grand mean: 716 ± 68 W, p = 0.800), or fatigue (grand mean: 66.5 ± 6.9%, p = 0.106). There was an effect of garment type on blood lactate in the sprint and the endurance trials (p < 0.05), although post hoc tests only detected a significant difference between the control and the nonionized conditions in the endurance trial (mean difference: 0.55 mmol·L, 95% likely range: 0.1-1.1 mmol·L). Relative to control, oxygen uptake (p = 0.703), heart rate (p = 0.774), and time trial performance (grand mean: 14.77 ± 0.74 minutes, p = 0.790) were unaffected by either type of compression garment during endurance cycling. Despite widespread use in sport, neither ionized nor nonionized compression tights had any significant effect on sprint or endurance cycling performance.     

Effects of two different half-squat training programs on fatigue during repeated cycling sprints in soccer players

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) performed 4 sets of 12 repetitions with 70% of 1RM, 3 times per week for 6 weeks, in addition to their common preseason training program. Repeated-sprint ability was assessed before and after training by 10 × 6-second cycle ergometer sprints separated by 24 seconds of passive recovery. Maximal half-squat strength increased significantly in both groups (p < 0.01), but this increase was significantly greater in the S-group compared with the H-group (17.3 ± 1.9 vs. 11.0 ± 1.9%, p < 0.05). Lean leg volume (LLV) increased only in the H-group. Total work over the 10 sprints improved in both groups after training, but this increase was significantly greater in the second half (8.9 ± 2.6%) compared with the first half of the sprint test (3.2 ± 1.7%) only in the S-group. Mean power output (MPO) expressed per liter of LLV was better maintained during the last 6 sprints posttraining only in the S-group, whereas there was no change in MPO per LLV in the H-group over the 10 sprints. These results suggest that resistance training with high loads is superior to a moderate-load program, because it increases strength without a change in muscle mass and also results in a greater improvement in repeated sprint ability. Therefore, resistance training with high loads may be preferable when the aim is to improve maximal strength and fatigue during sprinting in professional soccer players.     

The influence of recovery duration on multiple sprint cycling performance

The purpose of this study was to examine the influence of recovery duration on various measures of multiple sprint cycling performance. Twenty-five physically active men completed 2 maximal multiple sprint (20 x 5 seconds) cycling tests with contrasting recovery periods (10 or 30 seconds). The mean +/- SD values for age, height, and body mass were 20.6 +/- 1.5 years, 177.2 +/- 5.4 cm, and 78.2 +/- 8.2 kg, respectively. All tests were conducted on a friction-braked cycle ergometer. Longer (30 seconds) recovery periods resulted in significantly (p < 0.05) higher measures of maximum (approximately 4%) and mean (approximately 26%) power output, the former appearing to result from a potentiation effect during the first few sprints. Thirty-second recovery periods also corresponded with significantly lower measures of fatigue (absolute difference: 16.1%; 95% likely range: 14.1-18.2%), heart rate, respiratory exchange ratio, and oxygen uptake. Blood lactate and ratings of perceived exertion (6-20 scale) increased progressively throughout both protocols and were significantly lower with 30-second recovery periods. The results of this study illustrate the considerable influence of recovery duration on various measures of multiple sprint work. Although the precise mechanisms of this response require further investigation, coaches and sport scientists should consider these findings when attempting to develop or evaluate the performance capabilities of athletes involved in multiple sprint sports.     

Physiological responses during interval training with different intensities and duration of exercise

The purpose of this study was to compare 4 interval training (IT) sessions with different intensities and durations of exercise to determine the effect on mean VO?, total VO?, and duration of exertion ≥95% maximum power output (MPO), and the effects on biomarkers of fatigue such as blood-lactate concentration (BLC) and rating of perceived exertion. The subjects were 12 recreationally competitive male (n = 7, mean ± SD age = 26.2 ± 3.9 years) and female (n = 5, mean ± SD age = 27.6 ± 4.3 years) triathletes. These subjects performed 4 IT sessions on a cycle ergometer varying in intensity (90 and 100% MPO) and duration of exercise (30 seconds and 3 minutes). This study revealed that IT using 30-second duration intervals (30-30 seconds) allows the athlete to perform a longer session, with a higher total and mean VO? HR and lower BLC than 3-minute durations. Similarly, submaximal exertion at 90% of MPO also allows performing longer sessions with a higher total VO? than 100% intensity. Thus, the results of the present study suggested that to increase the total time at high intensity of exercise and total VO? of a single exercise session performed by the athlete, IT protocols of short durations (i.e., 30 seconds) and submaximal intensities (i.e., 90% MPO) should be selected. Furthermore, performing short-duration intervals may allow the athlete to complete a longer IT session with greater metabolic demands (VO?) and lower BLC than longer (i.e., 3 minutes) intervals.     

Effect of recovery interval on multiple-bout sprint cycling performance after acute creatine supplementation

The purpose of this study was to examine the effect of varying recovery intervals on multiple-bout, short-duration, high-intensity cycling efforts of adult men supplemented with creatine (Cr) or a placebo (Pl). Thirty subjects underwent 3 trials of a maximal cycling protocol (T(0), T(1), T(2)). T(0) included V(O)2 max testing and familiarization with the sprint cycling protocol. T(1) consisted of 8 15-second bouts of sprint cycling exercise. Subjects were randomly assigned to recovery interval groups (1 minute, 3 minutes, 6 minutes), and Cr or Pl groups (0.3 g x kg(-1) x d(-1)). Posttesting (T(2)) took place 7 days after T(1) and consisted of an identical protocol as during T(1). Changes in mean power (MP), peak power (PP), and fatigue index (FI) were compared between trials. MP was significantly increased in Cr 1-minute, Cr 3-minute, and Pl 6-minute groups (p < 0.05). Significant PP increases were demonstrated in Cr 1-minute and Pl 6-minute groups (p < 0.05), and FI significantly increased in Pl 1-minute group (p < 0.05). Results indicate that Cr supplementation is effective in improving recovery from repeated sprint cycling performances when the recovery interval is of a short (<6 minutes) duration.     

Aerobic and anaerobic correlates of multiple sprint cycling performance

The aims of this study were to examine (a) the relationship between maximal oxygen uptake (VO(2)max) and several performance indices of multiple sprint cycling; (b) the relationship between maximal accumulated oxygen deficit (MAOD) and those same performance indices; and (c) the influence of recovery duration on the magnitude of those relationships. Twenty-five physically active men completed a VO(2)max test, a MAOD test, and 2 maximal intermittent (20 x 5 seconds) sprint cycling tests with contrasting recovery periods (10 seconds or 30 seconds). Mean +/- SD for age, height, and body mass were 20.6 +/- 1.5 years, 177.2 +/- 5.4 cm, and 78.2 +/- 8.2 kg, respectively. All tests were conducted on a friction-braked cycle ergometer with subsequent data normalized for body mass. Moderate (0.3 < or = r < 0.5) positive correlations were observed between power output data and MAOD (range, 0.31-0.46; 95% confidence limits, -0.10 to 0.72). Moderate to large positive correlations also were observed between power output data and VO(2)max, the magnitude of which increased as values were averaged across all sprints (range, 0.45-0.67; 95% confidence limits 0.07-0.84). Correlations between fatigue and VO(2)max were greater in the intermittent protocol with 30-second recovery periods (r = -0.34; 95% confidence limits, 0.06 to -0.65). The results of this study reflect the complex energetics associated with multiple sprint work. Though the findings add support to the idea that multiple sprint sports demand a combination of speed and endurance, further longitudinal research is required to confirm the relative importance of these parameters.     

Are changes in maximal squat strength during preseason training reflected in changes in sprint performance in rugby league players?

Because previous research has shown a relationship between maximal squat strength and sprint performance, this study aimed to determine if changes in maximal squat strength were reflected in sprint performance. Nineteen professional rugby league players (height = 1.84 ± 0.06 m, body mass [BM] = 96.2 ± 11.11 kg, 1 repetition maximum [1RM] = 170.6 ± 21.4 kg, 1RM/BM = 1.78 ± 0.27) conducted 1RM squat and sprint tests (5, 10, and 20 m) before and immediately after 8 weeks of preseason strength (4-week Mesocycle) and power (4-week Mesocycle) training. Both absolute and relative squat strength values showed significant increases after the training period (pre: 170.6 ± 21.4 kg, post: 200.8 ± 19.0 kg, p < 0.001; 1RM/BM pre: 1.78 ± 0.27 kg·kg(-1), post: 2.05 ± 0.21 kg·kg(-1), p < 0.001; respectively), which was reflected in the significantly faster sprint performances over 5 m (pre: 1.05 ± 0.06 seconds, post: 0.97 ± 0.05 seconds, p < 0.001), 10 m (pre: 1.78 ± 0.07 seconds, post: 1.65 ± 0.08 seconds, p < 0.001), and 20 m (pre: 3.03 ± 0.09 seconds, post: 2.85 ± 0.11 seconds, p < 0.001) posttraining. Whether the improvements in sprint performance came as a direct consequence of increased strength or whether both are a function of the strength and power mesocycles incorporated into the players' preseason training is unclear. It is likely that the increased force production, noted via the increased squat performance, contributed to the improved sprint performances. To increase short sprint performance, athletes should, therefore, consider increasing maximal strength via the back squat.     

The influence of endurance training on multiple sprint cycling performance

The aims of the present study were to examine the effects of endurance training on multiple sprint cycling performance and to evaluate the influence of recovery duration on the magnitude of those effects. Twenty-one physically active male university students were randomly assigned to either an experimental (n = 12) or a control (n = 9) group. The experimental group cycled for 20 minutes each day, 3 times per week, for 6 weeks at 70% of the power output required to elicit maximal oxygen uptake (VO2max). Multiple sprint performance was assessed using 2 maximal (20 x 5 seconds) sprint cycling tests with contrasting recovery periods (10 or 30 seconds). All tests were conducted on a friction-braked cycle ergometer. Relative to controls, training resulted in a 0.2 L.min(-1) increase in mean VO2max (95% likely range: -0.04 to 0.44 L.min(-1)). Changes in anaerobic capacity (determined by maximal accumulated oxygen deficit) over the same period were trivial (p = 0.96). After training, the experimental group showed significant improvements ( approximately 40 W), relative to controls, in multiple sprint measures of peak and mean power output. In contrast, training-induced reductions in fatigue were trivial (p = 0.63), and there were no significant between-protocol differences in the magnitude of any effects. In summary, 6 weeks of endurance training resulted in substantial improvements in multiple sprint cycling performance, the magnitude of the improvements being largely unaffected by the duration of the intervening recovery periods.     

Complex training in ice hockey: the effects of a heavy resisted sprint on subsequent ice-hockey sprint performance

The aim of the study was to investigate the acute effect of a heavy resisted sprint when used as a preload exercise to enhance subsequent 25-m on-ice sprint performance. Eleven competitive ice-hockey players (mean ± SD: Age = 22.09 ± 3.05 years; Body Mass = 83.47 ± 11.7 kg; Height = 1.794 ± 0.060 m) from the English National League participated in a same-subject repeated-measures design, involving 2 experimental conditions. During condition 1, participants performed a 10-second heavy resisted sprint on ice. Condition 2 was a control, where participants rested. An electronically timed 25-m sprint on ice was performed before and 4 minutes after each condition. The results indicated no significant difference (p = 0.176) between pre (3.940 + 0.258 seconds) and post (3.954 + 0.261 seconds) sprint times in the control condition. The intervention condition, however, demonstrated a significant 2.6% decrease in times (p = 0.02) between pre (3.950 + 0.251 seconds) and post (3.859 + 0.288 seconds) test sprints. There was also a significant change (p = 0.002) when compared to the times of the control condition. These findings appear to suggest that the intensity and duration of a single resisted sprint in this study are sufficient to induce an acute (after 4 minutes of rest) improvement in 25-m sprint performance on ice. For those athletes wishing to improve skating speed, heavy resisted sprints on ice may provide a biomechanically suitable exercise for inducing potentiation before speed training drills.     

Higher muscle performance in adolescents compared with adults after a resistance training session with different rest intervals

The aim of the present study was to compare the effect of 3 different rest intervals between sets on the total training volume, number of repetitions, ratings of perceived exertion (RPE), and resistance to fatigue in adolescents and adults during a resistance training session in the isoinertial chest press exercise. Fifteen male adolescents (15.2 ± 1.2 years; 20.7 ± 2.0 kg·m(-2); Tanner -4; 61.5 ± 8.9, 10 repetition maximum [RM]) and 15 adults (22.2 ± 2.7 years; 23.3 ± 2.0 kg·m(-2); Tanner -5; 84.3 ± 13.5, 10RM) without previous experience with resistance training participated in the study. After 10RM test-retest on 3 different occasions, participants were randomly assigned to a resistance training protocol with 30-, 60-, and 120-second rest interval between sets. The protocol consisted of 3 sets with 10RM. In all studied variables, with exception to total training volume and RPE, adolescents presented superior results as compared with adults (p < 0.001). On the other hand, both adults and adolescents exhibited a higher resistance to fatigue, total training volume, and number of repetitions with a longer rest interval (120 > 60 > 30 seconds) (p < 0.01). Thus, these results indicate that adolescents present a higher recovery capacity between sets in a resistance training session than adults and a longer rest interval results in a higher number of repetitions completed, total training volume, and resistance to fatigue.     

Optimal elastic cord assistance for sprinting in collegiate women soccer players

Overspeed exercises are commonly integrated into a training program to help athletes perform at a speed greater than what they are accustomed to when unassisted. However, the optimal assistance for maximal sprinting has not been determined. The purpose of this study was to determine the optimal elastic cord assistance for sprinting performance. Eighteen collegiate women soccer players completed 3 testing sessions, which consisted of a 5-minute warm-up, followed by 5 randomized experimental conditions of 0, 10, 20, 30, and 40% body weight assistance (BWA). In all BWA sessions, subjects wore a belt while attached to 2 elastic cords and performed 2 maximal sprints under each condition. Five minutes of rest was given between each sprint attempt and between conditions. Split times (0-5, 5-10, 10-15, 15-20, and 0-20 yd) for each condition were used for analysis. Results for 0-20 yd demonstrated a significant main effect for condition. Post hoc comparisons revealed that as BWA increased, sprint times decreased up to 30% BWA (0%: 3.20 ± 0.12 seconds; 10%: 3.07 ± 0.09 seconds; 20%: 2.96 ± 0.07 seconds; 30%: 2.81 ± 0.08 seconds; 40%: 2.77 ± 0.10 seconds); there was no difference between 30 and 40% BWA. There was also a main effect for condition when examining split times. Post hoc comparisons revealed that as BWA increased, sprint times decreased up to 30% BWA for distances up to 15 yd. These results demonstrate that 30% of BWA with elastic cords appears optimal in decreasing sprint times in collegiate women soccer players for distances up to 15 yd.     

Similarity in adaptations to high-resistance circuit vs. traditional strength training in resistance-trained men

To compare the effects of 8 weeks of high-resistance circuit (HRC) training (3-6 sets of 6 exercises, 6 repetition maximum [RM], ～35-second interset recovery) and traditional strength (TS) training (3-6 sets of 6 exercises, 6RM, 3-minute interset recovery) on physical performance parameters and body composition, 33 healthy men were randomly assigned to HRC, TS, or a control group. Training consisted of weight lifting 3 times a week for 8 weeks. Before and after the training, 1RM strength on bench press and half squat exercises, bench press peak power output, and body composition (dual x-ray absorptiometry ) were determined. Shuttle run and 30-second Wingate tests were also completed. Upper limb (UL) and lower limb 1RM increased equally after both TS and HRC training. The UL peak power at various loads was significantly higher at posttraining for both groups (p ≤ 0.01). Shuttle-run performance was significantly better after both HRC and TS training, however peak cycling power increased only in TS training (p ≤ 0.05). Significant decreases were found in % body fat in the HRC group only; HRC and TS training both resulted in an increased lean but not bone mass. The HRC training was as effective as TS for improving weight lifting 1RM and peak power, shuttle-run performance and lean mass. Thus, HRC training promoted a similar strength-mass adaptation as traditional training while using a shorter training session duration.     

Combining explosive and high-resistance training improves performance in competitive cyclists

In several recent studies, athletes experienced substantial gains in sprint and endurance performance when explosive training or high-intensity interval training was added in the noncompetitive phase of a season. Here we report the effect of combining these 2 types of training on performance in the competitive phase. We randomized 18 road cyclists to an experimental (n = 9) or control (n = 9) group for 4-5 weeks of training. The experimental group replaced part of their usual training with twelve 30-minute sessions consisting of 3 sets of explosive single-leg jumps (20 for each leg) alternating with 3 sets of high-resistance cycling sprints (5 x 30 seconds at 60-70 min(-1) with 30-second recoveries between repetitions). Performance measures, obtained over 2-3 days on a cycle ergometer before and after the intervention, were mean power in a 1- and 4-km time trial, peak power in an incremental test, and lactate-profile power and oxygen cost determined from 2 fixed submaximal workloads. The control group showed little mean change in performance. Power output sampled in the training sprints of the experimental group indicated a plateau in the training effect after 8-12 sessions. Relative to the control group, the mean changes (+/-90% confidence limits) in the experimental group were: 1-km power, 8.7% (+/-2.5%); 4-km power, 8.1% (+/-4.1%); peak power, 6.8% (+/-3.6); lactate-profile power, 3.7% (+/-4.8%); and oxygen cost, -3.0% (+/-2.6%). Individual responses to the training were apparent only for 4-km and lactate-profile power (standard deviations of 2.5% and 2.8%, respectively). The addition of explosive training and high-resistance interval training to the programs of already well-trained cyclists produces major gains in sprint and endurance performance, partly through improvements in exercise efficiency and anaerobic threshold.     

Effects of 4 weeks of creatine supplementation in junior swimmers on freestyle sprint and swim bench performance

To determine whether 4 weeks of oral creatine (Cr) supplementation could enhance single freestyle sprint and swim bench performance in experienced competitive junior swimmers, 10 young men and 10 young women (x age = 16.4 +/- 1.8 years) participated in a 27-day supplementation period and pre- and posttesting sessions. In session 1 (presupplementation testing), subjects swam one 50-m freestyle and then (after approximately 5 minutes of active recovery) one 100-m freestyle at maximum speed. Blood lactate was measured before and 1 minute after each swim trial. Forty-eight hours later, height, mass, and the sum of 6 skinfolds were recorded, and a Biokinetic Swim Bench total work output test (2 x 30-second trials, with a 10-minute passive recovery in between) was undertaken. After the pretests were completed, participants were divided into 2 groups (n = 10, Cr; and n = 10, placebo) by means of matched pairs on the basis of gender and 50-m swim times. A Cr loading phase of 20 g x d(-1) for 5 days was then instituted, followed by a maintenance phase of 5 g x d(-1) for 22 days. Postsupplementation testing replicated the presupplementation tests. Four weeks of Cr supplementation did not influence single sprint performance in the pool or body mass and composition. However, 30-second swim bench total work scores for trial 1 and trial 2 increased after Cr (p < 0.05) but not placebo ingestion. Postexercise blood lactate values were not different after supplementation for the 50- and 100-m sprint trials either within or between groups. It was concluded that 4 weeks of Cr supplementation did not significantly improve single sprint performance in competitive junior swimmers, but it did enhance swim bench test performance.     

Growth hormone responses to repeated maximal cycle ergometer exercise at different pedaling rates.

The present study examined the growth hormone (GH) response to repeated bouts of maximal sprint cycling and the effect of cycling at different pedaling rates on postexercise serum GH concentrations. Ten male subjects completed two 30-s sprints, separated by 1 h of passive recovery on two occasions, against an applied resistance equal to 7.5% (fast trial) and 10% (slow trial) of their body mass, respectively. Blood samples were obtained at rest, between the two sprints, and for 1 h after the second sprint. Peak and mean pedal revolutions were greater in the fast than the slow trial, but there were no differences in peak or mean power output. Blood lactate and blood pH responses did not differ between trials or sprints. The first sprint in each trial elicited a serum GH response (fast: 40.8 +/- 8.2 mU/l, slow: 20.8 +/- 6.1 mU/l), and serum GH was still elevated 60 min after the first sprint. The second sprint in each trial did not elicit a serum GH response (sprint 1 vs. sprint 2, P < 0.05). There was a trend for serum GH concentrations to be greater in the fast trial (mean GH area under the curve after sprint 1 vs. after sprint 2: 1,697 +/- 367 vs. 933 +/- 306 min x mU(-1) x l(-1); P = 0.05). Repeated sprint cycling results in an attenuation of the GH response.     

Kinematic and kinetic analysis of maximal velocity deadlifts performed with and without the inclusion of chain resistance

The purpose of this study was to investigate whether the deadlift could be effectively incorporated with explosive resistance training (ERT) and to investigate whether the inclusion of chains enhanced the suitability of the deadlift for ERT. Twenty-three resistance trained athletes performed the deadlift with 30, 50, and 70% 1-repetition maximum (1RM) loads at submaximal velocity, maximal velocity (MAX), and MAX with the inclusion of 2 chain loads equal to 20 or 40% of the subjects' 1RM. All trials were performed on force platforms with markers attached to the barbell to calculate velocity and acceleration using a motion capture system. Significant increases in force, velocity, power, rate of force development, and length of the acceleration phase (p < 0.05) were obtained when repetition velocity increased from submaximal to maximal. During MAX repetitions with a constant resistance, the mean length of the acceleration phase ranged from 73.2 (±7.2%) to 84.9 (±12.2%) of the overall movement. Compared to using a constant resistance, the inclusion of chains enabled greater force to be maintained to the end of the concentric action and significantly increased peak force and impulse (p < 0.05), while concurrently decreasing velocity, power, and rate of force development (p < 0.05). The effects of chains were influenced by the magnitude of the chain and barbell resistance, with greater increases and decreases in mechanical variables obtained when heavier chain and barbell loads were used. The results of the investigation suggest that the deadlift can be incorporated effectively in ERT programs. Coaches and athletes should be aware that the inclusion of heavy chains may have both positive and negative effects on kinematics and kinetics of an exercise.     

A biomechanical analysis of straight and hexagonal barbell deadlifts using submaximal loads

The purpose of the investigation was to compare the kinematics and kinetics of the deadlift performed with 2 distinct barbells across a range of submaximal loads. Nineteen male powerlifters performed the deadlift with a conventional straight barbell and a hexagonal barbell that allowed the lifter to stand within its frame. Subjects performed trials at maximum speed with loads of 10, 20, 30, 40, 50, 60, 70, and 80% of their predetermined 1-repetition maximum (1RM). Inverse dynamics and spatial tracking of the external resistance were used to quantify kinematic and kinetic variables. Subjects were able to lift a heavier 1RM load in the hexagonal barbell deadlift (HBD) than the straight barbell deadlift (SBD) (265 ± 41 kg vs. 245 ± 39 kg, p < 0.05). The design of the hexagonal barbell significantly altered the resistance moment at the joints analyzed (p < 0.05), resulting in lower peak moments at the lumbar spine, hip, and ankle (p < 0.05) and an increased peak moment at the knee (p < 0.05). Maximum peak power values of 4,388 ± 713 and 4,872 ± 636 W were obtained for the SBD and HBD, respectively (p < 0.05). Across the submaximal loads, significantly greater peak force, peak velocity and peak power values were produced during the HBD compared to during the SBD (p < 0.05). The results demonstrate that the choice of barbell used to perform the deadlift has a significant effect on a range of kinematic and kinetic variables. The enhanced mechanical stimulus obtained with the hexagonal barbell suggests that in general the HBD is a more effective exercise than the SBD.     

Caffeine and sprinting performance: dose responses and efficacy

The aims of this study were to evaluate the effects of caffeine supplementation on sprint cycling performance and to determine if there was a dose-response effect. Using a randomized, double-blind, placebo-controlled design, 17 well-trained men (age: 24 ± 6 years, height: 1.82 ± 0.06 m, and body mass(bm): 82.2 ± 6.9 kg) completed 7 maximal 10-second sprint trials on an electromagnetically braked cycle ergometer. Apart from trial 1 (familiarization), all the trials involved subjects ingesting a gelatine capsule containing either caffeine or placebo (maltodextrin) 1 hour before each sprint. To examine dose-response effects, caffeine doses of 2, 4, 6, 8, and 10 mg·kg bm(-1) were used. There were no significant (p ≥ 0.05) differences in baseline measures of plasma caffeine concentration before each trial (grand mean: 0.14 ± 0.28 μg·ml(-1)). There was, however, a significant supplement × time interaction (p < 0.001), with larger caffeine doses producing higher postsupplementation plasma caffeine levels. In comparison with placebo, caffeine had no significant effect on peak power (p = 0.11), mean power (p = 0.55), or time to peak power (p = 0.17). There was also no significant effect of supplementation on pretrial blood lactate (p = 0.58), but there was a significant time effect (p = 0.001), with blood lactate reducing over the 50 minute postsupplementation rest period from 1.29 ± 0.36 to 1.06 ± 0.33 mmol·L(-1). The results of this study show that caffeine supplementation has no effect on short-duration sprint cycling performance, irrespective of the dosage used.     

Squat jump training at maximal power loads vs. heavy loads: effect on sprint ability

Training at a load maximizing power output (Pmax) is an intuitively appealing strategy for enhancement of performance that has received little research attention. In this study we identified each subject's Pmax for an isoinertial resistance training exercise used for testing and training, and then we related the changes in strength to changes in sprint performance. The subjects were 18 well-trained rugby league players randomized to two equal-volume training groups for a 7-week period of squat jump training with heavy loads (80% 1RM) or with individually determined Pmax loads (20.0-43.5% 1RM). Performance measures were 1RM strength, maximal power at 55% of pretraining 1RM, and sprint times for 10 and 30 m. Percent changes were standardized to make magnitude-based inferences. Relationships between changes in these variables were expressed as correlations. Sprint times for 10 m showed improvements in the 80% 1RM group (-2.9 +/- 3.2%) and Pmax group (-1.3 +/- 2.2%), and there were similar improvements in 30-m sprint time (-1.9 +/- 2.8 and -1.2 +/- 2.0%, respectively). Differences in the improvements in sprint time between groups were unclear, but improvement in 1RM strength in the 80% 1RM group (15 +/- 9%) was possibly substantially greater than in the Pmax group (11 +/- 8%). Small-moderate negative correlations between change in 1RM and change in sprint time (r approximately -0.30) in the combined groups provided the only evidence of adaptive associations between strength and power outputs, and sprint performance. In conclusion, it seems that training at the load that maximizes individual peak power output for this exercise with a sample of professional team sport athletes was no more effective for improving sprint ability than training at heavy loads, and the changes in power output were not usefully related to changes in sprint ability.