International journal of sports physiology and performance最新文献

Purpose: Although previous studies have compared strength-training adaptations between free weights (FW) and machine-guided exercises, those studies did not use a Smith machine (SM), which most closely replicates the exercises performed with FW. Thus, the aim of the present study was to investigate the chronic effects of strength-focused, velocity-based training regimens using FW versus SM.

Methods: Thirty-seven sport-science students (14 female) were assigned, balanced by sex and relative strength, to either an FW or SM training group. The training program lasted 8 weeks (2 sessions/wk), and participants performed 4 sets per exercise (back squat and bench press) at 70% of their 1-repetition maximum with moderate effort levels (20%-25% velocity loss). Load-velocity profile parameters (load-axis intercept, velocity-axis intercept, and area under the load-velocity relationship line), cross-sectional areas of the vastus lateralis and pectoralis major muscles, and the number of repetitions to failure in the bench-press exercise were assessed before and after the training program. Mechanical variables were assessed using both FW and SM.

Results: All variables, with the exception of back-squat velocity-axis intercept (P = .124), improved in both training groups. The changes in load-axis intercept and area under the load-velocity relationship line were more pronounced when the training and testing conditions matched. Failure in the bench-press exercise and cross-sectional areas of the vastus lateralis and pectoralis major showed comparable improvements for both training groups, while velocity-axis intercept tended to improve more in the SM group.

Conclusions: The general population, unconcerned with the specificity of strength adaptations, can choose a training modality (FW or SM) based on personal preferences.

Purpose: The purpose of this research was to report isometric hip adduction and abduction strength reference values of men's and women's Gaelic football and rugby union players and compare values between sexes and between sports.

Methods: This cross-sectional cohort study consisted of 331 club-level athletes. Maximum isometric hip adduction squeeze and abduction press strength values were measured with a ForceFrame across several testing positions.

Results: Hip adduction squeeze and abduction press strength reference values for men's and women's Gaelic and rugby union footballers were provided with mean and 1 SD. A 2-way analysis of variance demonstrated significant sport × sex interaction main effects for hip adduction squeeze (η2 = .159-.228), abduction press (η2 = .099-.144), and adduction:abduction ratio (η2 = .120). Men demonstrated significantly greater relative (Newtons per kilogram) maximum isometric hip adduction squeeze (15.5%-26.4%, 0.48-1.00 N/kg) and hip abduction press (9.6%-19.6%, 0.20-0.67 N/kg) strength across all testing positions when compared with women of the same sport. Male Gaelic football players demonstrated significantly greater hip adduction (8.7%-14.0%, 0.30-0.52 N/kg) and abduction (6.1%-8.6%, 0.16-0.31 N/kg) strength (Newtons per kilogram) than their rugby counterparts, while no significant between-sports differences in strength were observed between female athletes.

Conclusion: Reference values are provided with mean and 1 SD. Sport and sex interaction had significant main effects for hip adduction, abduction, and adduction:abduction ratio, with medium to large effect sizes. Male athletes demonstrate significantly greater hip strength than female athletes of the same sport, and male Gaelic players demonstrate greater hip strength than male rugby players.

Purpose: Two new designs of track spikes have recently emerged: spikes with a compliant and resilient midsole foam (eg, polyether block amide [PEBA]) and spikes that combine such modern foam with a carbon fiber plate. We evaluated the effect of these different spikes on running performance measures for middle- and long-distance track events in trained runners.

Methods: Fourteen females on a single visit performed six 200-m trials at a self-perceived 800-m race pace in 3 different spike conditions (Control, PEBA, and PEBA + Plate), twice in a mirrored order. Sixteen males completed 4 visits. During each of the first 3 visits, they performed six 200-m trials at a self-perceived 800-m race pace, twice in each condition, followed by a 3000-m time trial in 1 of the 3 spike conditions. During visit 4, participants completed six 4-minute running-economy trials at 5 m/s, twice in each condition.

Results: At the 800-m race pace, females ran faster in PEBA (2.1%) and PEBA + Plate (2.0%) compared with Control. Males ran faster in PEBA (1.4%) and PEBA + Plate (2.4%) compared with Control and in PEBA + Plate compared with PEBA (1.1%). Similarly, males ran the 3000-m time trial faster in PEBA (1.0%) and PEBA + Plate (2.4%) than in Control. Running economy was better in PEBA (5.1%) and PEBA + Plate (4.0%) than in Control.

Conclusions: Compared with traditional spiked shoes, shoes with PEBA foam (both with and without a plate) enhanced distance-running performance measures by 1% to 2% in females and males, with greater benefits in the PEBA + Plate condition in males.

Purpose: In rowing, the effectiveness of adding high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT) within the weekly training program on physiological adaptations and performance is still unclear. This study compared the effects of HIIT plus MICT (MIXED) versus MICT alone on physiological/metabolic responses and performance in adolescents.

Methods: Twelve highly trained adolescent rowers (age: 15.7 [0.5] y) were divided into 2 groups: MIXED and MICT. Before and after a 7-week intervention period, rowers underwent an incremental step test to determine peak oxygen uptake (VO2peak), power at VO2peak (WVO2peak), power corresponding to a lactate concentration of 2 and 4 mmol·L-1, power output at lactate threshold, oxygen uptake at the second lactate threshold (VO2LT), and peak oxygen pulse. Training load from TRIMP was also measured. The training intervention consisted of 7 sessions per week including 2 "off-water," 3 "on-water," and 2 resistance-training sessions. The "on-water" and resistance-training sessions were the same for both groups, while during "off-water" sessions, the MIXED group performed HIIT (4 × 4 min at 85% WVO2peak) and the MICT group performed moderate-intensity training (80 min at 70% WVO2peak).

Results: Statistical analysis showed that in the MIXED group, VO2LT was significantly increased and training load from TRIMP was significantly reduced (P < .00001) compared with the MICT group (P = .008). Both groups similarly improved VO2peak, peak oxygen pulse, WVO2peak, power output at lactate threshold, and power corresponding to a lactate concentration of 2 and 4 mmol·L-1.

Conclusions: Our findings showed that, in adolescent rowers, MIXED training enhanced VO2LT, thus indicating HIIT as a valid and time-efficient addition to traditional MICT. However, given that adolescents were examined, data should be interpreted with caution, as training and/or growth/maturation may have contributed to performance changes.

Purpose: We evaluated the technical and energetical impact of using Randall foils versus simple Big blades during a maximum rowing effort in field conditions.

Methods: Fourteen experienced rowers (12 male and 2 female) 26 (9) versus 25 (9) years of age, 179.8 (4.3) versus 175.0 (2.8) cm in height, and 74.2 (4.8) versus 65.5 (6.2) kg of body mass (for males and females, respectively) performed 2 maximal 500-m on-water bouts (1 each using Randall foils and simple Big blades in a randomized order). Performance and physiological variables were continuously measured along the efforts, with the latter being also recorded during the baseline and recovery periods.

Results: Rowing time was shorter using Randall foils when compared with simple Big blades (107.59 [5.53] vs 108.96 [5.44] s), while cycle rate (39.73 [2.56] vs 39.71 [2.24] cycle·min-1), peak oxygen uptake (63.47 [9.96] vs 62.68 [9.65] mL·kg-1·min-1), mean oxygen uptake (4.15 [0.77] vs 4.12 [0.78] L·min-1), respiratory frequency (62.44 [9.22] vs 62.17 [11.22] beats·min-1), peak heart rate (178 [11] vs 180 [9] beats·min-1], peak blood lactate concentration (14.26 [3.52] vs 13.76 [4.02] mmol · L-1), and rating of perceived effort (17 [1.43] vs 17 [1]) were similar in both experimental conditions. Furthermore, it was observed that the aerobic pathway represented ∼50% of the total energy spent in the 500-m sprint independently of the blades used.

Conclusions: Data suggest that the use of Randall foils enhances rowing performance without compromising rowers' mechanical and metabolic functions.

Purpose: Feedback is information that is provided to aid reflection and learning and enhance future performances. Due to the increased demands of professional soccer and governance around staffing structures, the number of stakeholders delivering and receiving feedback has grown over the past 2 decades. The aim of the present study was to explore the feedback strategies used in professional men's soccer in England.

Methods: One hundred thirty-nine respondents comprising coaches (n = 34), players (n = 39), and performance staff (n = 66) from the English Premier League and football leagues completed an online survey. The survey included 19 questions on giving and receiving feedback.

Results: Daily verbal interactions such as conversations and informal chats were the primary source of feedback and were highly prevalent between the 3 groups (59%-80%). Feedback was delivered frequently (daily/weekly) by all stakeholders at regular time points (before, during, and after training and matches), with >75% of coaches reporting giving feedback at all time points. Two-way feedback was also prevalent, with >76% of participants delivering or receiving feedback 2 ways.

Conclusions: The data highlighted the importance of verbal communication within the process of optimizing professional soccer players' development and performance. Professional soccer clubs should focus on interpersonal and intrapersonal skill development and an approach that facilitates positive interactions between staff and players within the optimal environment (ie, time and space). We recommend further exploration of stakeholders' perceptions and effectiveness of feedback in influencing decision making and informing behavior change.

Purpose: To quantify the relationship between load models during official games of the novel 3 × 3 basketball sport.

Methods: Forty-one adult male players were monitored across three 3 × 3 basketball official tournaments. Players wore Firstbeat Sports microsensors to quantify external (Movement Load) and internal physiological (summated-heart-rate-zones [SHRZ]) loads. Additionally, rating of perceived exertion (RPE) scores were obtained after each game to calculate session RPE (sRPE) loads as internal perceived load. Repeated-measures correlation analyses were performed to assess the relationships between Movement Load and internal loads (SHRZ and sRPE), and between SHRZ and sRPE.

Results: External load (Movement Load) and internal physiological load (SHRZ) had a very large correlation (r = .76, P < .001). External load was also largely correlated with internal perceived load (sRPE; r = .57, P < .001). The correlation between SHRZ and sRPE was moderate (r = .47, P < .001).

Conclusion: During 3 × 3 basketball games, large to very large relationships exist between external- and internal-load variables. This information allows practitioners to anticipate internal responses of players to games based on the external load imposed, thus optimizing training-load prescription strategies.

Purpose: To provide insights into a dose-response relationship between training and time-trial performance, as assessed in both a "fresh" and a "fatigued" state (durability), including proposed underlying factors for durability: gross efficiency and substrate oxidation (FatOx and CarbOx).

Methods: Ten male semiprofessional cyclists underwent a performance test in both "fresh" and "fatigued" state (after 38.6 [4.6] kJ·kg-1) before and after an 8-week training period, containing the measurement of gross efficiency, FatOx, and CarbOx at submaximal intensity and maximal time trials of 1 (PO1) and 10 minutes (PO10). Relationships were assessed with the session rating of perceived exertion, kilojoules spent, Lucia training impulse, Training Stress Score, polarization index, and time spent in 3 zones in the intervening period.

Results: No significant relationship was found between higher training load and performance on PO1 and PO10, with a large variation between assessed training-load measures and individual participants. However, CarbOx showed a strong correlation with training volume in the "fresh" state and with time spent below first-lactate-threshold intensity in the "fatigued" state. Also, the relationship between training load and change in performance between tests showed different trends for "fresh" compared with "fatigued" state, especially for FatOx and CarbOx.

Conclusions: The fact that no clear relationships between dose (training) and response (time-trial performance) were shown in this study indicates that a single load measure is not able to predict performance improvements after an 8-week training period. However, the current study shows that the same training can have a different effect on "fresh" versus "fatigued" performance, having implications for the design of training plans.

Objectives: This study aimed to report (1) the correlation between net metabolic cost (NMC) of running and Achilles tendon (AT) and ankle plantar flexor passive stiffness and (2) explore the relationship between passive stiffness and key running biomechanics.

Methods: Twenty-two male recreational runners participated in this study. The runners performed a 5-minute run at 50% of their maximal aerobic speed as a warm-up on an instrumented treadmill, followed by a 6-minute run at 65% of their maximal aerobic speed wherein NMC was recorded. Passive stiffness was measured using a myotonometry device both before and after the run.

Results: There was a negative linear relationship between NMC and AT stiffness. NMC and prerun AT stiffness demonstrated a significant negative correlation between leg stiffness and a significant positive correlation with braking peak force and step length. Moreover, we observed an increase in stiffness between prerun and postrun measurements at rest for the AT and both gastrocnemius muscles.

Conclusion: Greater AT stiffness measured at rest is correlated with lower NMC.