AIM:Aim of the present study was to investigate performance and kinematics of cross-country skiers during sprint running and bounding on different inclines, in relationship to maximal strength, power and skiing performance.METHODS:On day one, the maximal strength of 14 elite skiers was tested using a mid-thigh isometric pull and maximal relative leg power determined using squat and countermovement jumps. Day two involved 15-m maximal sprints and 5-step bounding at 0º, 7.5° and 15º inclines. From video recordings sprint, step, contact and flight times; step length and frequency; total number of sprint steps and average bounding velocity were determined. Skiing performance was assessed using International Ski Federation (FIS) points from the preceding season and compared to strength, power, bounding and sprint performance, and kinematics.RESULTS:On steeper inclines sprint time was higher and bounding distance shorter (both P<0.001), and step frequency during sprinting and bounding, reduced and increased respectively (P<0.001). Isometric maximal strength correlated strongly with bounding distance on the two steeper inclines (r=0.76 and 0.83). Squat and countermovement jump heights correlated moderately with sprint performance at both 7° and 15°, and bounding performance on all three inclines (r=0.55-0.65). The distance bounded uphill correlated moderately with FIS points (r=-0.55 and -0.67).CONCLUSION:Incline influenced sprinting and bounding performance and kinematics. Maximal leg power is important for both sprinting and bounding uphill, while maximal strength is important for the latter. The skiers with better FIS rankings bounded farther on steeper inclines, suggesting that this capacity is beneficial for cross-country skiing performance.

This study examined two active coolings (forearm and hand cooling, and neck cooling) during a simulated half-time recovery on thermoregulatory responses and subsequent soccer-specific exercise performance. Following a 45-min treadmill run in the heat, participants (N= 7) undertook 15-min recovery with either passive cooling, forearm and hand cooling, or neck cooling in a simulated cooled locker room environment. After the recovery, participants performed a 6x15-m sprint test and Yo-Yo Intermittent Recovery Level 1 test (YYIR1) in a temperate environment. During the 15-min recovery, rectal temperature fell significantly (p< 0.05). Neither active coolings induced further reduction in rectal temperature compared to passive cooling. No effect of active coolings was found in repeated sprint test. However, neck cooling reduced (p< 0.05) the thermal sensation (TS) compared to passive cooling during the 15-min recovery. Active coolings attenuated (p< 0.05) the sweat rate compared to passive cooling: 1.2 +/- 0.3 l center dot h(-1) vs. 0.8 +/- 0.1 l center dot h(-1) vs. 0.8 +/- 0.3 l center dot h(-1), for passive cooling, forearm and hand cooling, and neck cooling, respectively. For passive cooling, elevated sweat rate resulted in higher (p< 0.05) dehydration (2.1 +/- 0.3%) compared to neck cooling (1.5 +/- 0.3%) and forearm and hand cooling (1.4 +/- 0.3%). YYIR1 was improved (p< 0.05) following forearm and hand cooling (869 +/- 320 m) and neck cooling (814 +/- 328 m) compared to passive cooling (654 +/- 311 m). Neck cooling (4.6 +/- 0.6) reduced (p= 0.03) the session TS compared to passive cooling (5.3 +/- 0.5). These results suggest that active coolings effectively improved comfort and sweating response, which delayed exercise-heat induced performance diminish during a second bout of exercise.

Effect of different inclines on sprinting, bounding, and one-leg hopping performance in endurance-trained athletes

Laurent, CM, Green, JM, Bishop, PA, Sjokvist, J, Schumacker, RE, Richardson, MT, and Curtner-Smith, M. A practical approach to monitoring recovery: development of a perceived recovery status scale. J Strength Cond Res 25(3): 620-628, 2011-The aim of this study was to develop and test the practical utility of a perceived recovery status (PRS) scale. Sixteen volunteers (8 men, 8 women) performed 4 bouts of high-intensity intermittent sprint exercise. After completion of the baseline trial, in a repeated-measures design, subjects were given variable counterbalanced recovery periods of 24, 48, and 72 hours whereupon they repeated an identical intermittent exercise protocol. After a warm-up period, but before beginning each subsequent bout of intermittent sprinting, each individual provided their perceived level of recovery with a newly developed PRS scale. Similar to perceived exertion during exercise, PRS was based on subjective feelings. The utility of the PRS scale was assessed by measuring the level of agreement of an individual's perceived recovery relative to their performance during the exercise bout. Perceived recovery status and change (both positive and negative) in sprint performance during multiple bouts of repeated sprint exercise were moderately negative correlated (r = -0.63). Additionally, subjects were able to accurately assess level of recovery using the PRS scale indicated by correspondence with negative and positive changes in total sprint time relative to their previous session. The ability to detect changes in performance using a noninvasive psychobiological tool to identify differences in performance was independent of other psychological and physiological markers measured during testing, because there were no differences (p > 0.05) among ratings of perceived exertion (RPE), heart rate, blood lactate concentration, or session RPE values among any of the performance trials. Although further study is needed, current results indicate a subjective approach may be an effective means for assessing recovery from day to day, at least under similar conditions.

This study quantified the performance recovery time requirements after training sessions using high-intensity soccer drills with and without the ball in National Collegiate Athletic Association Division I female soccer players. Recovery time periods (24, 48, 72 hours of rest) from high-intensity soccer training sessions using drills with and without the ball were evaluated. Markers of recovery were each individual's performance relative to baseline performance in countermovement jump (CMJ) height, 5 bound jumps for distance (5BT), 20-m sprint (20SP), session rating of perceived effort (S-RPE), and heart rate (HR). Repeated-measures analysis of variance revealed a significant difference in CMJ performance (p < 0.04) and S-RPE (p < 0.02) after 24 hours of rest but not at 48 or 72 hours compared to baseline. There were no significant differences in 20SP, 5BT, or HR after 24, 48, or 72-hour recovery (p > 0.05). Therefore, high-intensity training drills produced a sufficient conditioning stimulus with little chance of underrecovery for the performance measures we tested. Countermovement jump and S-RPE may be more sensitive performance recovery indicators.

The current investigation examined the potential teleoanticipatory effect on perceptual response during repeated bouts of maximal sprint work. To determine the consistency of ratings of perceived exertion (RPE) increase during identical exercise bouts following variable recovery periods, 16 (8 men, 8 women) participants completed four separate trials of repeated maximal sprinting on 4 separate days utilizing different recovery periods. Following completion of the baseline trial, participants were given variable, counter-balanced recovery periods of 24, 48 and 72 hours, whereupon they repeated the intermittent exercise protocol. To determine the degree of similarity among trials, each individual's rate of RPE progression during each cycle of eight sprints throughout the recovery trials were compared to the rate of progression during the baseline exercise session. A series of 4 (trial) x 3 (cycle of sprints) repeated measures ANOVA were performed to identify significant main effects between trials and among cycles while session RPE was analyzed using one-way repeated measures ANOVA. Fisher's least significant difference post-hoc procedures were performed to identify where significant differences occurred when appropriate. Results revealed an inconsistency in the stability of RPE across repeated bouts of sprint exercise, with at least 50% of individuals having a substantial difference in RPE (i.e. +/- 1 unit change) in at least one subsequent trial. These variations in perceptual responses were observed despite a concomitant stability of physiological and performance responses between sessions. Results suggest that rate of RPE increase correspond more closely to increased or decreased physiologic strain than to an anticipatory, feed-forward mechanism following variable recovery durations. [J Exerc Sci Fit . Vol 8 . No 1 . 1-10 . 2010]

AIM This study investigated the effects of gender on repeated, maximal-intensity intermittent sprint exercise following variable day-to-day recovery periods. METHODS Sixteen volunteers (8 men, 8 women) performed four trials of high-intensity intermittent sprint exercise consisting of three bouts of eight 30 m sprints (total of 24 sprints). Following completion of the baseline trial, in repeated-measures design, participants were assigned, in counter-balanced order, variable recovery periods of 24, 48, and 72 h whereupon they repeated an identical exercise trial. RESULTS Results from a series of 4 (trial) x 3 (bout) repeated measures ANOVAs revealed men produced significantly (P < 0.01) faster times throughout all bouts and trials of repeated sprint exercise. Additionally, women exhibited significantly lower (P < 0.05) blood lactate concentration and significantly lower (P < 0.05) decrement in performance, indicating increased resistance to fatigue during repeated exercise sessions. There were no significant differences (P > 0.05) between genders for heart rate or rating of perceived exertion during or following trials. There were no significant differences for overall sprint performance within either gender among trials. CONCLUSION These results indicate men, while able to produce higher absolute power outputs (i.e., lower sprint time), demonstrate higher decrement scores within a trial compared to women, thus suggesting women may recover faster and fatigue less. Also, gender differences affecting recovery within in a trial were observed to be diminished between trials (i.e., day-to-day recovery) of maximal intermittent sprint work evidenced by the observed stability of performance between trials following various recovery durations.