Investigating the Relevance of Maximal Speed and Acceleration in Varsity-Level Female Ice Hockey Players.

PURPOSE: To characterize and compare female ice hockey players' peak skating speed and acceleration ability during linear sprints and gameplay. We also sought to quantify the time spent at various speeds and the frequency of accelerations at different thresholds during games. METHODS: Seventeen varsity-level female ice hockey players (20 [1.4] y, 68.9 [4.9] kg, 167.6 [4.7] cm) participated in an on-ice practice session (performing 3 × 40-m linear sprints) and 4 regular-season games while being monitored using a local positioning system. Speed and acceleration were recorded from the sprint and within-game monitoring. Time on ice spent in relative skating speed zones and the frequency of accelerations at different intensities were recorded. RESULTS: Players' greatest peak speeds (29.5 [1.3] vs 28.3 [1.1] km/h) and accelerations (4.39 [0.48] vs 3.34 [0.36] m/s2) reached during gameplay were higher than those reached in linear sprinting (both P < .01). Peak in-game values were moderately predicted by linear sprint values for speed (r = .69, P < .01) but not for acceleration (r < .01, P = .95). Players spent little time at near-peak linear sprint speeds (≥80% [22.7 km/h], ∼3% time on ice; ≥90% [25.5 km/h], <1% of time on ice) during gameplay. However, 26% to 35% of accelerations recorded during the 4 games were ≥90% of linear sprint acceleration. CONCLUSIONS: Although skating speed may be advantageous in specific game situations, our results suggest that players spend little time at near-maximal speeds while accelerating frequently during games. This warrants further investigation of direction changes, skating transitions, repeated sprints, and other determinant variables potentially related to on-ice success and the implementation of training strategies to improve repeated acceleration or qualities beyond maximal skating speed.

Food for thought: Physiological considerations for nutritional ergogenic efficacy.

Top-class athletes have optimized their athletic performance largely through adequate training, nutrition, recovery, and sleep. A key component of sports nutrition is the utilization of nutritional ergogenic aids, which may provide a small but significant increase in athletic performance. Over the last decade, there has been an exponential increase in the consumption of nutritional ergogenic aids, where over 80% of young athletes report using at least one nutritional ergogenic aid for training and/or competition. Accordingly, due to their extensive use, there is a growing need for strong scientific investigations validating or invalidating the efficacy of novel nutritional ergogenic aids. Notably, an overview of the physiological considerations that play key roles in determining ergogenic efficacy is currently lacking. Therefore, in this brief review, we discuss important physiological considerations that contribute to ergogenic efficacy for nutritional ergogenic aids that are orally ingested including (1) the impact of first pass metabolism, (2) rises in systemic concentrations, and (3) interactions with the target tissue. In addition, we explore mouth rinsing as an alternate route of ergogenic efficacy that bypasses the physiological hurdles of first pass metabolism via direct stimulation of the central nervous system. Moreover, we provide real-world examples and discuss several practical factors that can alter the efficacy of nutritional ergogenic aids including human variability, dosing protocols, training status, sex differences, and the placebo effect. Taking these physiological considerations into account will strengthen the quality and impact of the literature regarding the efficacy of potential ergogenic aids for top-class athletes.

Reliability and validity of an indoor local positioning system for measuring external load in ice hockey players.

This study determined the reliability and validity of a Kinexon local positioning system (LPS) for measuring external load in ice hockey players during an on-ice session. Fourteen ice hockey players (25.1 y, 78.6 kg, 176.9 cm) wore two LPS sensors to examine the inter-sensor reliability of the LPS during an on-ice session, and LPS speed and acceleration were measured during 40 m linear on-ice sprints and compared to a previously validated robotic sprint device to examine LPS accuracy. The coefficient of variation (CV), standard error of measurement (SEM), and intra-class correlation coefficient (ICC) were calculated for each LPS measure. Pearson's correlations, simple linear regressions, and Bland-Altman plots were used to test the agreement and relationship between the two systems. Statistical significance was determined at p < 0.05. The majority of LPS measures were reliable (CV < 10% and ICC > 0.9) when comparing the two sensors worn by each player. Peak speed, speed at 5 m, and 0-5 m acceleration were all comparable to those reported by the robotic sprint device, with nearly perfect (peak speed and 0-5 m acceleration) and very large (speed at 5 m) magnitudes of correlation and mean biases <0.5 km/hr for speed measures and <0.01 m/s2 for acceleration. The present results demonstrate that the Kinexon LPS is reliable and accurate for investigating on-ice external load in ice hockey players when sensors are consistently secured on the back of the players' shoulder pads.

Dietary Intake of Young Male Ice Hockey Players 10-13 Years of Age during a Week-Long Hockey Camp.

This study recorded the dietary intakes of young male ice hockey players (10-13 year (yr)) for 3 consecutive days while participating in a 5-day summer hockey camp. Players were categorized as older children (OC, n = 10; 10.7 ± 0.2 yr; 37.1 ± 1.5 kg; 147.9 ± 2.1 cm) and young adolescents (YA, n = 10; 12.9 ± 0.1 yr; 45.2 ± 1.5 kg; 157.0 ± 2.4 cm). Players consumed their usual daily intakes. Parents recorded food intake in the mornings and evenings, while the researchers recorded food intake at camp. Energy intake was higher in both groups when compared to data for age-matched young Canadian (CDN) males (OC, 2967 ± 211 vs. 2000 kcal/day; YA, 2773 ± 91 vs. 2250 kcal/day). Carbohydrate (CHO) (OC, 11.2 ± 0.8 vs. YO, 8.9 ± 0.5 g/kg body mass/day) and protein (OC, 3.2 ± 0.3; YO, 2.4 ± 0.1 g/kg/day) intakes were higher than reported for young CDN males (CHO, 3.6 and protein, 1.0 g/kg/day) and were within the Acceptable Macronutrient Distribution Range (AMDR; CHO, 56 ± 2.3; 57.4 ± 0.8%; protein, 16.1 ± 1.0; 15.7 ± 0.7%). Fat intake was also within the AMDR in both groups (OC, 29.8 ± 1.6%; YA, 28.3 ± 1.0%). Micronutrient intake was adequate except for Vitamin D intakes that were below the recommended 15 ug/day at 6.3 ± 0.7 (OC) and 5.0 ± 1.5 ug/day (YA). In summary, energy and macronutrient intakes of the OC (10-11 yr) and YA (12-13 yr) players were high and well above the age matched CDN norms. The older children had higher energy intakes/kg body mass than the young adolescents. Higher energy intakes allowed for micronutrients intakes to be met in these young active males, except for vitamin D intake.

Dietary Intake over a 7-Day Training and Game Period in Female Varsity Rugby Union Players.

This study estimated the daily energy intake (EI) and energy expenditure (TDEE) in female varsity rugby union players during a weekly training/game cycle. Fifteen (nine forwards, six backs) players (20.5 ± 0.4 y, 167.1 ± 1.8 cm, 74.9 ± 2.9 kg) were monitored for a 7-day period (one fitness, two heavy training, one light training, one game, and two recovery days) during their regular season. The average EI throughout the week for all 15 players was 2158 ± 87 kcal. There were no significant differences between days, but the lowest EI (1921 ± 227 kcal) occurred on the mid-week recovery day and the highest on game day (2336 ± 231 kcal). The average TDEE was 2286 ± 168 kcal (~6% > EI). The mean energy availability (EA) over the 7-day period was 31.1 ± 3.6 kcal/kg FFM/day for the group. Of the players, 14% were in the optimal EA range (>45 kcal/kg FFM/day); 34% were in the moderate range (≥30−45 kcal/kg FFM/day); and 52% had a poor EA of <30 kcal/kg FFM/day. Carbohydrate (3.38 ± 0.36 g/kg/day, 45% of EI); fat (1.27 ± 0.12 g/kg/day, 37% of EI); and protein (1.38 ± 0.12 g/kg/day, 18% of EI) consumption remained similar throughout the week (p > 0.05). The players consumed 6% less energy than they expended, providing poor to moderate EA; therefore, daily carbohydrate intake recommendations were not met.

Local Positioning System-Derived External Load of Female and Male Varsity Ice Hockey Players During Regular Season Games.

Purpose: The purposes of this study were to quantify the external load for female and male varsity ice hockey players during regular season games using a local positioning system (LPS), compare LPS-derived external load between sexes and positions, and compare skating distances in absolute and relative speed zones. Methods: Data were collected for 21 female (7 defense, 14 forwards; 20.0 ± 1.4 yrs., 69.1 ± 6.7 kg, 167.1 ± 5.4 cm) and 25 male (8 defense, 17 forwards; 21.9 ± 1.1 yrs., 85.9 ± 5.4 kg, 181.1 ± 5.2 cm) varsity ice hockey players. Measures included skating distance (total, and in absolute and relative speed zones), peak skating speed, peak acceleration and deceleration, accumulative acceleration load, and number of accelerations, decelerations, turns, skating transitions, direction changes, and impacts. Results: Female and male players had a high external load during games, with average peak skating speeds >28 km/h and average skating distances >4.4 km. Most LPS-derived measures showed greater external load in males than females (p < 0.05). Forwards skated further at higher speeds compared to defense in both sexes (p < 0.001). Skating distances were significantly different when comparing absolute and relative speed zones (p < 0.001), with absolute speed zones potentially overestimating skating at very slow, very fast, and sprint speeds and underestimating skating at slow and moderate speeds. Conclusion: This was the first study to measure external load in female ice hockey players with a LPS. Both female and male varsity players had high external loads during games, with forwards having greater external load at higher intensities and defense having greater external load at lower intensities. Sex and positional differences outline the importance of individualized athlete monitoring.

Carbohydrate Mouth-Rinsing Improves Overtime Physical Performance in Male Ice Hockey Players During On-Ice Scrimmages.

PURPOSE: This randomized, double-blind, crossover study examined the effects of mouth-rinsing (MR) with a carbohydrate (CHO) vs. a placebo (PLA) solution on external and internal loads in hydrated ice hockey players during regulation and overtime (OT) periods of an on-ice scrimmage. METHODS: Twelve skilled male hockey players (22.6 [3.4] years, 178.9 [4.7] cm, 84.0 [6.5] kg) played three 20-min regulation periods and one 12-min OT period of small-sided 3-on-3 scrimmage. Skaters repeated 2 min shift and rest intervals. Participants mouth rinsed with 25 mL of CHO or PLA solution approximately every 10 min for a total of 7 rinses. A local positioning system (LPS) tracked external load variables including speed, distance, acceleration, and deceleration. Internal load was monitored with heart rate (HR) sensors and a rating of perceived exertion (RPE). RESULTS: During regulation play, both the conditions developed similar fatigue, with significantly decreased high-intensity distance, average speed and decelerations, and increased RPE, from period 1 to 2 and 3. In OT, CHO MR increased the distance skated at high-intensity (224 [77], 185 [66] m, p = 0.042), peak speed (24.6 [1.6], 23.7 [1.3] km·h-1, p = 0.016), number of sprints (1.9 [1.2], 1.2 [0.9], p = 0.011), and decreased distance skated at slow speed (300 [33], 336 [47], p = 0.034) vs. PLA MR. OT RPE was similar between the two conditions in spite of more work done in CHO MR. CONCLUSIONS: CHO MR may be a valuable practice to protect against decrements in external load with increased playing time in ice hockey, and possibly allows athletes to perform more work relative to perceived levels of exertion.

External Training Demands in Women's Varsity Rugby Union Players Quantified by Wearable Microtechnology With Individualized Speed Thresholds.

ABSTRACT: Nyman, DLE and Spriet, LL. External training demands in women's varsity rugby union players quantified by wearable microtechnology with individualized speed thresholds. J Strength Cond Res 36(11): 3151-3158, 2022-This study used wearable Global Positioning System (GPS) microtechnology with individualized speed thresholds to examine external training demands in 29 female varsity rugby union athletes during competitive season practices. Players were categorized as forwards or backs and observed during fitness, game-based, or skill training days (FT/GT/ST). Global Positioning System-derived variables included distances, high-intensity running (HIR), work-to-rest ratio, power plays, and PlayerLoad. Five speed zones categorized athlete movements and were customized according to each individual's overall maximum velocity (V̇max). Compared with backs, forwards had lower overall V̇max (6.62 ± 0.66 m·s -1 ; 7.38 ± 0.61 m·s -1 , p = 0.003) and HIR thresholds (3.97 ± 0.40 m·s -1 ; 4.43 ± 0.37 m·s -1 , p = 0.003). There were no interaction effects between position and training day for any GPS-derived variables. However, there were several effects of position ( p ≤ 0.05), with forwards being lower than backs in mean V̇max, zone 1 distance, and power plays, and greater than backs in zone 3, zone 4, and HIR distances. Effects of the training day ( p ≤ 0.05) were also observed in zone 1 distance, with FT being lower than GT and ST, and in power plays, with FT being greater than ST. In female varsity rugby union athletes, there were significant positional differences in individualized speed thresholds and external training demands. However, there were few marked differences between fitness, game-based, and skill training days.

Internal Load of Female Varsity Ice Hockey Players During Training and Games During a Season.

This study quantified internal load, using sessional rating of perceived exertion (sRPE) and heart-rate derived training impulse (TRIMP), of female varsity ice hockey players throughout a season. Twenty-four female (19.8±1.4 yr, 68.0±6.9 kg) varsity ice hockey players participated in this prospective cohort study. Internal load was captured using sRPE and TRIMP for each on-ice session. Internal load was significantly higher (p<0.05) for games (sRPE: 324±202 AU, TRIMP: 95±60 AU) compared to training (sRPE: 248±120 AU, TRIMP: 68±32 AU). Overall, goalies had a higher internal load than forwards (sRPE and TRIMP) and defence (TRIMP), with no differences between forwards and defence. Micro-cycle periodization was present, with training sessions several days prior to game days having the highest internal load (sRPE and TRIMP) and tapering down as subsequent training sessions approached game day. For the meso-cycle assessment, for both training and competition combined, the post-season sRPE was greater than the pre-season (p=0.002) and regular season (p<0.001). Lastly, the association between sRPE and TRIMP, revealed a large, statistically significant relationship (r=0.592, p<0.001). Internal load was greater during competitions, training sessions and subsequent internal loads suggested prioritization around game days, the post-season phase demanded the highest internal load and there was a strong correlation between sRPE and TRIMP.

Internal Load of Male Varsity Ice Hockey Players During Training and Games Throughout an Entire Season.

PURPOSE: The purpose of this study was to quantify the internal load of male varsity ice hockey players, using both sessional rating of perceived exertion (sRPE) and the heart rate-derived physiological measure of training impulse (TRIMP), during training sessions and competitions throughout an entire season. METHODS: Twenty-seven male varsity ice hockey players (22.1 [1.1] y, 85.9 [5.4] kg, 181.3 [5.1] cm) were included in this longitudinal prospective cohort study. RESULTS: The internal load was significantly higher (P < .001) for games (sRPE: 403 [184] arbitrary units [AU], TRIMP: 98 [59] AU) compared with training sessions (sRPE: 281 [130] AU, TRIMP: 71 [35] AU). The regular season had the highest internal load compared with the preseason and postseason. There was evidence of microcycle periodization with training sessions several days prior to game days having the highest internal load (both sRPE and TRIMP) and tapering down as the subsequent training sessions approached game day. For positional comparisons, the goalies had higher sRPE (346 [151] AU, P < .001) and TRIMP (99 [64] AU, P < .001) compared with defense (sRPE: 295 [130] AU, TRIMP: 65 [29] AU) and forwards (sRPE: 264 [123] AU, TRIMP: 70 [30] AU) for training sessions, but no significant differences were present for competitions. Finally, there was an overall moderate and statistically significant relationship between the sRPE and TRIMP internal load measures (r = .434, P < .001). CONCLUSIONS: Internal load was greater during competitions versus training sessions in male varsity ice hockey players, and the microcycle assessment demonstrated that training sessions were tailored to game day. Mesocycle assessment revealed the highest internal loads during the regular season due to dense game scheduling and a short season.

Potential effect of beetroot juice supplementation on exercise economy in well-trained females.

This study examined if acute dietary nitrate supplementation (140 mL beetroot juice, BRJ) would reduce oxygen consumption (V̇O2) during cycling at power outputs of 50 and 70% maximal oxygen consumption in 14 well-trained female Canadian University Ringette League athletes. BRJ had no effect on V̇O2 or heart rate but significantly reduced ratings of perceived exertion (RPE) at both intensities. Individually, 4 participants responded to BRJ supplementation with a ≥3% reduction in V̇O2 at the higher power output. Novelty: Acute BRJ supplementation did not improve exercise economy in well-trained females, but significantly reduced RPE. However, 4/14 subjects did respond with a ≥3% V̇O2 reduction.

Internal Physiological Load Measured Using Training Impulse in Varsity Men's and Women's Ice Hockey Players Between Game Periods.

ABSTRACT: Bigg, JL, Gamble, ASD, and Spriet, LL. Internal physiological load measured using training impulse in varsity men's and women's ice hockey players between game periods. J Strength Cond Res 35(10): 2824-2832, 2021-This study quantified internal load in male and female ice hockey players throughout a season, with comparisons between game periods and match outcome. Twenty-seven male and 24 female varsity ice hockey players participated in this longitudinal prospective cohort study monitoring internal load, using Banister's training impulse (TRIMP). Data were assessed according to game periods, match outcome (win or loss), and games played in noncongested (1 game/wk) or congested (2 + games/wk) weeks. Statistical significance was considered at p < 0.05. The TRIMP for period 1 for both male (25 ± 16 arbitrary units [AU]) and female (23 ± 19 AU) players was significantly lower than period 3 (males: 30 ± 21 AU; p = 0.001; females: 29 ± 21 AU; p = 0.003) but not period 2 (males: 27 ± 17 AU; p = 0.183; females: 27 ± 19 AU; p = 0.681). There were no differences in TRIMP within any period between games resulting in a win compared with a loss. Overall, there were no differences in TRIMP between male and female players. However, when stratified by position, male forwards experienced greater TRIMP than female forwards (p < 0.001 for all periods), whereas female defense had greater TRIMP than male defense (p ≤ 0.032 for all periods). There were no differences between noncongested and congested week games and no differences in TRIMP between nonback-to-back and back-to-back games, or the first and second games played of a back-to-back series. This study measured physiological demand throughout the periods of ice hockey games in men and women and concluded that internal load was highest in the third period. Understanding the demands throughout a game can provide information to coaches and players that would be useful in managing fatigue and optimizing physical performance.

Dietary Macronutrient and Micronutrient Intake over a 7-Day Period in Female Varsity Ice Hockey Players.

This study examined the energy, macronutrient, and micronutrient intakes of female ice hockey players over a 7-d period including game, practice, and rest days. Twenty-three female varsity players (19.0 ± 1.1 yr, 167.1 ± 6.5 cm, 67.0 ± 8.0 kg) volunteered for the study. Average total daily energy expenditure (TDEE) was estimated over the 7-day period. Average 7-day energy intake (EI) and TDEE were 2354 ± 353 and 2304 ± 204 kcal. The majority (n = 19) of athletes had an EI ≥ 90% of their estimated TDEE. Macronutrient intake was 52% carbohydrate (CHO), 32% fat, and 16% protein of total EI, although CHO intake was slightly below recommendations (5 g/kg BM/d) on game and practice (4.8 ± 1.4 and 4.5 g/kg BM/d) days. Game day EI was greater than practice and rest days. Recommended micronutrient intakes were not met by most athletes for iron, calcium, vitamin D, and potassium, and intakes were similar between game, practice, and rest days. In summary, the average EI for female varsity ice hockey players appeared adequate to meet their energy needs over a weekly cycle of game, practice, and rest days. However, these female athletes would benefit from increasing CHO intake on game and practice days and selecting foods that are rich in vitamins and minerals.

The torque-frequency relationship is impaired similarly following two bouts of eccentric exercise: No evidence of a protective repeated bout effect.

High-intensity eccentric exercise can lead to muscle damage and weakness. The 'repeated bout effect' (RBE) can attenuate these impairments when performing a subsequent bout. The influence of eccentric exercise-induced muscle damage on low-frequency force production is well-characterized; however, it is unclear how eccentric exercise and the RBE affect torque production across a range of stimulation frequencies (i.e., the torque-frequency relationship). We investigated the influence of an initial (Bout 1) and repeated bout (Bout 2) of eccentric exercise on the elbow flexor torque-frequency relationship. Eleven males completed two bouts of high-intensity eccentric elbow flexions, 4 weeks apart. Torque-frequency relationships were constructed at baseline and 0.5, 24, 48, 72, 96, and 168 h following both bouts via percutaneous stimulation at 1, 6, 10, 20, 30, 40, 50, and 100 Hz. Serum creatine kinase activity, self-reported muscle soreness, and isometric maximum voluntary contraction torque indirectly inferred the presence of muscle damage following Bout 1, and attenuation of muscle damage following Bout 2. Torque amplitude at all stimulation frequencies was impaired 30 min following eccentric exercise, however, torque at lower (1-10 Hz) and higher frequencies (40-100 Hz) recovered within 24 h while torque across the middle frequency range (20-30 Hz) recovered by 48 h. No between-bout differences were detected in absolute or normalized torque at any stimulation frequency, indicating no protective RBE on the elbow flexor torque-frequency relationship.

Muscle Glycogen Metabolism and High-Intensity Exercise Performance: A Narrative Review.

Muscle glycogen is the main substrate during high-intensity exercise and large reductions can occur after relatively short durations. Moreover, muscle glycogen is stored heterogeneously and similarly displays a heterogeneous and fiber-type specific depletion pattern with utilization in both fast- and slow-twitch fibers during high-intensity exercise, with a higher degradation rate in the former. Thus, depletion of individual fast- and slow-twitch fibers has been demonstrated despite muscle glycogen at the whole-muscle level only being moderately lowered. In addition, muscle glycogen is stored in specific subcellular compartments, which have been demonstrated to be important for muscle function and should be considered as well as global muscle glycogen availability. In the present review, we discuss the importance of glycogen metabolism for single and intermittent bouts of high-intensity exercise and outline possible underlying mechanisms for a relationship between muscle glycogen and fatigue during these types of exercise. Traditionally this relationship has been attributed to a decreased ATP resynthesis rate due to inadequate substrate availability at the whole-muscle level, but emerging evidence points to a direct coupling between muscle glycogen and steps in the excitation-contraction coupling including altered muscle excitability and calcium kinetics.

Moderate Load Resisted Sprints Do Not Improve Subsequent Sprint Performance in Varsity-Level Sprinters.

ABSTRACT: Thompson, K, Whinton, AK, Ferth, S, Spriet, LL, and Burr, JF. Moderate load resisted sprints do not improve subsequent sprint performance in varsity-level sprinters. J Strength Cond Res 35(1): 72-77, 2021-Resisted sprint training (RST) is commonly used for performance enhancement in athletics and team sports to develop acceleration ability. Evidence suggests that RST may be effective as a short-term intervention to improve successive sprints. Although these improvements have been measured in team sport athletes, limited research has considered the acute effects of RST training in sprint-trained athletes. Therefore, the aim of the current study was to determine whether performing RST with varsity-level sprinters using sled-equivalent resistive loads of ∼45% body mass results in a potentiation effect, leading to improvements in subsequent maximal sprint performance over 0-5 m and 0-20 m. Competitive sprinters (n = 20) were randomly assigned to perform a pre/post maximal 20-m sprint separated by either 3 resisted (RST group) or unresisted (URS group) sprints. The RST or URS protocol was performed on 4 occasions separated by at least 7 days. No significant differences were observed between the RST and URS groups comparing changes in sprint times over 0-5 m (URS Δ <0.01 ± 0.03 seconds, RST Δ <0.01 ± 0.03 seconds) and 0-20 m (URS Δ 0.013 ± 0.04 seconds, RST Δ <0.01 ± 0.04 seconds). We conclude that resisted sprints using sled-equivalent loads of 45% body mass are ineffective at inducing a potentiating effect on subsequent sprint performance in varsity-level sprinters. In this population of trained athletes, greater loads may be necessary to induce a potentiating effect.

Chronic pantothenic acid supplementation does not affect muscle coenzyme A content or cycling performance.

This study determined if supplementation with pantothenic acid (PA) for 16 weeks could increase skeletal muscle coenzyme A (CoASH) content and exercise performance. Trained male cyclists (n = 14) were matched into control or PA (6 g·day-1) groups. At 0, 4, 8, and 16 weeks, subjects performed an incremental time to exhaustion cycle with muscle biopsies taken prior to and following exercise. Prolonged PA supplementation did not change skeletal muscle CoASH and acetyl-CoA contents or exercise performance. Novelty: Supplementation with pantothenic acid for 16 weeks had no effect on skeletal muscle CoASH and acetyl-CoA content or exercise performance in trained male cyclists.