The relationship of training load to physical-capacity changes during international tours in high-performance junior tennis players

Change-of-Direction Speed Assessments and Testing Procedures in Tennis: A Systematic Review

ABSTRACT

Schneider, C, Rothschild, J, and Uthoff, A. Change-of-direction speed assessments and testing procedures in tennis: a systematic review. J Strength Cond Res 37(9): 1888-1895, 2023-Change-of-direction speed (CODS) plays an essential role in tennis match play, and CODS performance is, therefore, commonly assessed and monitored in tennis players. Thus, the aim of this systematic review was to describe test characteristics, performance metrics, test-retest reliability, construct validity, and test outcomes of tests that are used to assess CODS in tennis players. A literature search conducted on PubMed and SPORTDiscus yielded 563 results. After applying the eligibility criteria, a total of 27 studies were included in the present review. Ten unique CODS tests were identified. 505 test variations were most frequently used across all studies, and total time required to complete the test was the predominant performance metric investigated. Intrasession test-retest reliability ranged from "moderate" to "excellent." Intersession test-retest reliability as well as the effects of tennis performance, sex, and age on CODS performance were unclear given the subject demographics and the limited number of studies that investigated these aspects. In conclusion, most studies included CODS tests that exhibit longer COD entry and total distances but similar COD angles to those seen during tennis match play. All CODS tests have at least "moderate" intrasession test-retest reliability. However, to improve CODS assessment methods and to increase our current understanding of CODS performance in tennis players, there is a need to conduct more research on the intersession test-retest reliability, construct validity, and the effects of sex, age, and tennis performance and to investigate other performance metrics that might provide additional insights into CODS (e.g., phase-specific performance variables).

Methods of Monitoring Internal and External Loads and Their Relationships with Physical Qualities, Injury, or Illness in Adolescent Athletes: A Systematic Review and Best-Evidence Synthesis

BACKGROUND

With the increasing professionalisation of youth sports, training load monitoring is increasingly common in adolescent athletes. However, the research examining the relationship between training load and changes in physical qualities, injury, or illness in adolescent athletes is yet to be synthesised in a systematic review.

OBJECTIVE

The aim of this review was to systematically examine the research assessing internal and external methods of monitoring training load and physical qualities, injury, or illness in adolescent athletes.

METHODS

Systematic searches of SPORTDiscus, Web of Science, CINAHL and SCOPUS were undertaken from the earliest possible records to March 2022. Search terms included synonyms relevant to adolescents, athletes, physical qualities, injury, or illness. To be eligible for inclusion, articles were required to (1) be original research articles; (2) be published in a peer-reviewed journal; (3) include participants aged between 10 and 19 years and participating in competitive sport; (4) report a statistical relationship between a measure of internal and/or external load and physical qualities, injury or illness. Articles were screened and assessed for methodological quality. A best-evidence synthesis was conducted to identify trends in the relationships reported.

RESULTS

The electronic search yielded 4125 articles. Following screening and a review of references, 59 articles were included. The most commonly reported load monitoring tools were session ratings of perceived exertion (n = 29) and training duration (n = 22). Results of the best-evidence synthesis identified moderate evidence of positive relationships between resistance training volume load and improvement in strength, and between throw count and injury. However, evidence for other relationships between training load and change in physical qualities, injury, or illness were limited or inconsistent.

CONCLUSIONS

Practitioners should consider monitoring resistance training volume load for strength training. Additionally, where appropriate, monitoring throw counts may be useful in identifying injury risk. However, given the lack of clear relationships between singular measures of training load with physical qualities, injury, or illness, researchers should consider multivariate methods of analysing training load, as well as factors that may mediate the load-response relationship, such as maturation.

Linear and Change of Direction Repeated Sprint Ability Tests: A Systematic Review

ABSTRACT

Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this review was to identify overground RSA protocols previously reported in the literature and to recommend standardized protocols. A systematic review of the literature was used to identify studies that have used an RSA test, with data describing protocol design extracted. One hundred eight studies were included in the review, across which 47 unique protocols were identified. Eighteen protocols included at least one change of direction (COD), and this increased mean sprint time compared with linear RSA tests (7.26 ± 1.84 vs. 4.48 ± 1.02 seconds). There was considerable variability across protocols regarding sprint distance (20-40 m), sprint repetitions (3-15), recovery duration (10-60 seconds), recovery type (active vs. passive), and work-to-rest ratio (≤1:1.4-19.2). Separate protocols are needed for linear and COD tests, and these should reflect the brief nature of intense periods of competition and stress the ability to recover. Based on data across studies for protocol design and to ensure a demanding work-to-rest ratio, it is suggested that a linear RSA should comprise 6 × 30 m sprints separated by 15 seconds of active recovery. To provide some parity to linear tests, to keep work duration brief and to maintain a demanding work-to-rest ratio, a COD RSA should comprise 6 × 30 m shuttle sprints (15 + 15 m), providing one change of direction (180° COD), and maintaining a 15-second active recovery.

Effects of a Six-Week International Tour on the Physical Performance and Body Composition of Young Chilean Tennis Players

In tennis, it is common for young male tennis players to spend several weeks away from their local training camps during the competition season, which could affect their performance. The purpose of the study was to analyze the effects of a six-week international tour on physical performance and body composition in young Chilean tennis players. Twenty-four men between the ages of 14 and 16 participated in this research. In body composition and anthropometric measurement, body weight, height, skinfolds, and perimeters were measured. Body fat percentage (BFP) and skeletal muscle mass (SMM) were calculated. For physical performance, 5-m and 10-m sprints, modified agility test (MAT test), countermovement jump (CMJ), and medicine ball throw (MBT) were evaluated. Results show that, in body composition, BFP and SMM significantly decreased post-tour (p < 0.05; effect sizes ranging from 0.23 to 0.33, respectively). In physical performance, agility and 5-m and 10-m sprints significantly decreased (p < 0.05, effect sizes ranging from −0.63 to 1.10). We conclude that after a six-week international tour, BFP, SMM, agility, and speed (linear sprint) tend to decrease significantly, with a greater effect in the sprint tests.

Determining Stroke and Movement Profiles in Competitive Tennis Match-Play From Wearable Sensor Accelerometry

ABSTRACT

Perri, T, Reid, M, Murphy, A, Howle, K, and Duffield, R. Determining stroke and movement profiles in competitive tennis match-play from wearable sensor accelerometry. J Strength Cond Res XX(X): 000-000, 2023-This study determined stroke and movement accelerometry metrics from a wearable sensor and compared between court surface (grass vs. hard) and match outcome (win vs. loss) during competitive tennis match-play. Eight junior high-performance tennis players wore a trunk-mounted global positioning system, with in-built accelerometer, magnetometer, and gyroscope during singles matches on hard and grass courts. The manufacturer software calculated accelerometer-derived total player load (tPL). A prototype algorithm classified forehands, backhands, serves, and "other" strokes, thereby calculating stroke PL (sPL) from individual strokes. Movement PL (mPL) was calculated as the difference between tPL and sPL, with all metrics reported as absolute and relative (min -1 , %, and ·stroke). Analysis of accelerometer load and stroke count metrics was performed through a two-way (surface [grass vs. hard] × match outcome [win vs. loss]) analysis of variance ( p < 0.05) and effect sizes (Cohen's d ). No interaction effects for surface and match outcome existed for absolute tPL, mPL, and sPL ( p > 0.05). Increased mPL% featured on grass courts, whereas sPL% was increased on hard courts ( p = 0.04, d = 1.18[0.31-2.02]). Elevated sPL·min -1 existed on hard courts ( p = 0.04, d = 1.19[0.32-2.04]), but no differences in tPL·min -1 and mPL·min -1 were evident for surface or outcome ( p > 0.05). Relative forehand sPL (FH-sPL·min -1 ) was higher on hard courts ( p = 0.03, d = 1.18[0.31-2.02]) alongside higher forehand counts ( p = 0.01, d = 1.29[0.40-2.14]). Hitting demands are heightened on hard courts from increased sPL and counts. Conversely, increased mPL% on grass courts likely reflects the specific movement demands from point-play. Physical preparation strategies during training blocks can be tailored toward movement or hitting loads to suit competitive surfaces.

Competition scheduling patterns of emerging elite players in professional men's tennis

This study analysed the competition scheduling of future top 100 and 250 ranked tennis players from international tournament profiles at ages 13-18y. Retrospective tournament data were analysed for 165 future top 100 (T100) and top 250 (T250) males during their junior international tournament eligibility. Tournament/match volumes, days between tournaments and consecutive tournaments (<8 days between) were quantified for junior and professional events. A two-way (age x ranking) analysis of variance determined the effects of age and ranking group on tournament profiles. Significant interactions were observed for tournament volumes across junior and professional categories, with T100 players competing in professional tournaments earlier (p<0.05). No significant interactions were observed for volumes of junior or professional matches played (p>0.05). No significant interactions were observed for days between tournaments or consecutive tournaments played (p>0.05). Significant main effects were observed for age on tournament volume, with junior and professional volume increasing at age 15 and 17, respectively (p<0.05). Higher match volumes were observed for T100 players compared to T100-S players (p<0.05). Competition schedules intensify at age 15 compared with ages 13-14y through increased tournament and match volumes. Future T100 players' transition to professional tournaments earlier, alongside greater engagement in higher quality junior tournaments.

Minimal Agreement between Internal and External Training Load Metrics across a 2-wk Training Microcycle in Elite Squash

This study investigated the relationships between internal and external training load metrics across a 2-week 'in-season' microcycle in squash. 134 on-court and 32 off-court 'conditioning' sessions were completed by fifteen elite squash players with an average (±SD) of 11 ± 3 per player. During every session, external load was captured using a tri-axial accelerometer to calculate Playerload; i.e., the instantaneous rate of change of acceleration across 3-dimensional planes. Internal load was measured using heart rate (HR), global (sRPE) and differential RPE (dRPE-Legs, dRPE-Breathing). Additionally, HR was used to calculate Banister's, Edward's and TEAM TRIMPs. Across 166 training sessions, Playerload was moderately correlated with TRIMP-Banister (r = 0.43 [95% CI: 0.29-0.55], p < 0.001) and TRIMP-Edwards (r = 0.50 [0.37-0.61], p < 0.001). Association of Playerload with TRIMP-TEAM (r = 0.24 [0.09-0.38], p = 0.001) was small. There was a moderate correlation between sRPE and Playerload (r = 0.46 [0.33-0.57], p < 0.001). Association of sRPE was large with TRIMP-Banister (r = 0.68 [0.59-0.76], p = 0.001), very large with TRIMP-Edwards (r = 0.79 [0.72-0.84], p < 0.001) and moderate with TRIMP-TEAM (r = 0.44 [0.31-0.56], p < 0.001). Both dRPE-Legs (r = 0.95 [0.93-0.96], p < 0.001) and dRPE-Breathing (r = 0.92 [0.89-0.94], p < 0.001) demonstrated nearly perfect correlations with sRPE and with each other (r = 0.91 [0.88-0.93], p < 0.001). Collection of both internal and external training load data is recommended to fully appreciate the physical demands of squash training. During a training microcycle containing a variety of training sessions, interpreting internal or external metrics in isolation may underestimate or overestimate the training stress a player is experiencing.

The Effect of Training Loads on Performance Measures and Injury Characteristics in Rugby League Players: A Systematic Review

PURPOSE

To conduct a systematic review into the effect of training load (TL) on both performance measures and injury characteristics in rugby league players.

METHODS

Based on PRISMA guidelines, a systematic search of electronic databases was performed from the earliest record to December 2016. Five electronic databases (MEDLINE, SPORTDiscus, CINAHL, Web of Science, and AusSportMed) were searched using keywords within the subcategories of population (rugby league players), intervention (training quantification), and outcomes (performance or injury). Original peer-reviewed published manuscripts were considered if they had a clear quantification of TL (eg, session rating of perceived exertion), clear measures of performance (tests of physiological parameters relative to rugby league players [eg, agility]), and/or injury characteristics (eg, injury incidence).

RESULTS

Twelve studies met the inclusion criteria. The highest TL was observed in preseason training phases. Higher TL elicited greater improvements in maximal aerobic power, vertical jump (in cm), and agility scores (in s). Higher TL was associated with higher incidence of muscular strains and joint sprains, lower-limb injuries, and overexertion and overuse injuries.

CONCLUSIONS

Findings suggest a dose-response relationship between TL, physical performance, and injury characteristics. However, due to study and methodological limitations, the precise nature of this relationship is, as yet, inconclusive. Therefore, the development of uniform TL definition and quantification and further research is warranted.

Impact of a competition with two consecutive matches in a day on physical performance in young tennis players

The purpose of this study was to analyze the effects of playing 2 tennis matches on the same day on physical performance in young tennis players. Twelve well-trained young tennis players took part in a simulated tennis competition consisting of 2 tennis matches on the same day (morning and afternoon sessions). Before and the day after the competition, physical performance was measured using a battery of countermovement jumps; a 10 m sprint; the 5-0-5 agility test; hip, grip and shoulder maximal isometric strength; shoulder range of motion; and a serve velocity test. Postcompetition results showed reduced performance in 10 m (-3.3%, effect size (ES) = small), dominant and nondominant 5-0-5 agility test (-4.6%, ES = moderate; -4.2%, ES = moderate, respectively), bilateral (-5.2%, ES = small), and unilateral countermovement jumps (dominant leg: -7.2%, ES = small; non-dominant leg: -9.1%, ES = small). Both dominant and nondominant shoulder external rotation range of motion increased (12.2%, ES = moderate; 5.6%, ES = small), whereas internal rotation decreased (-4.2%, ES = small; -3.3%, ES = small) in the postcompetition tests, together with the dominant shoulder external rotation (-10.7%, ES = moderate) and internal rotation (-9.3%, ES = small) strength. Physical impairments occurred in neuromuscular performance variables involving lower (e.g., jumping, sprinting, and change of direction) and upper (e.g., isometric strength and range of motion) limbs the day after playing a competition with 2 consecutive matches on the same day. These alterations in neuromuscular and sport-specific performance need to be taken into consideration when planning tournament schedules for young tennis players, as well as preparing match and recovery strategies.

Physiological Responses of Young Tennis Players to Training Drills and Simulated Match Play

The aim of this study was to investigate the responses of young tennis players during 5 different training drills and to compare the responses between drills. Ten (17.0 ± 1.2 years) male tennis players participated in this study. Each athlete completed 5 total training drills. Drills 1-4 consisted of each player returning balls from a ball-serving machine and were stroke/time-controlled over 6 points. The fifth drill was a simulated match (SM) play, between 2 opposing players, and also lasted 6 points. The 4 stroke/time-controlled drills had the following strokes/time for each point: drill 1: 2 strokes/∼4 seconds, drill 2: 4 strokes/∼8 seconds, drill 3: 7 strokes/∼14 seconds, drill 4: 10 strokes/∼20 seconds. Peak heart rate (HR), blood lactate concentration (LA), and rating of perceived exertion (RPE) were measured after the first, third, and sixth point of each drill. Drills were performed in a randomized crossover design; a 2-way repeated-measures analysis of variance was used with significance set at p ≤ 0.05. All dependent variables (HR, LA, and RPE) significantly increased (p ≤ 0.05) as strokes, and time per rally increased in each drill. Furthermore, all variables were elevated to a greater magnitude (p ≤ 0.05) during the 7 and 10 stroke drills after the first, third, and sixth points when compared with the SM and the 2 and 4 stroke drills at the corresponding time points. These results suggest that the physiological responses to tennis training drills were stroke/time-dependent. Therefore, because of the intense intermittent nature of tennis, stroke/time-controlled drills, which require significant physiological demands, should be incorporated along with technically focused shorter drills to fully mimic the conditions of competitive match play.