Comparisons of countermovement jump force profiles in youth athletes

Gillen, Zachary M.; McHugh, Malachy P.; Shoemaker, Marni E.; Cramer, Joel T.

doi:10.1002/tsm2.257

Cited by 5 publications

(14 citation statements)

References 42 publications

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“…In contrast, isokinetic muscle strength testing provides information on a range of muscle properties. 8 The model can evaluate the properties of muscles under concentric and eccentric contractions.…”

Section: Resultsmentioning

confidence: 99%

Isokinetic Kneel Muscle Strength Characteristics in High Jump Athletes

2023

Rev Bras Med Esporte

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Introduction: Vertical jump is inherent to the practice of high jump and demands great capacity of force generation and work of the knee muscles, especially the quadriceps muscle. Due to this demand, imbalances between the extensor and flexor knee muscles may be present, leading to an overload of the musculotendinous structures of the knee joint. Therefore, it is necessary to establish the characteristics of isokinetic muscle strength in the knee joint of these athletes. Objective: This study aimed to analyze the biomechanical properties of the knee flexor and extensor muscles in high jump athletes. Methods: Ten high jumpers volunteered for the experiment. They were divided into experimental and control groups. Both groups performed basic strength training. The experimental group added isokinetic knee muscle training based on this training. Statistical analyses were performed on the training data of the two groups of athletes using relevant mathematical statistics. Results: The high jump consists of four phases being respectively the approach run, the jump itself (impulsion, elevation, transposition), and the fall. The strength of the ankle joint dorsiflexion and plantar flexors was significantly increased in the experimental group of athletes. In contrast, the strength of the plantar flexors in the control group was significantly increased. Statistical differences were found between the two groups (P<0.05). Conclusion: The isokinetic knee joint strength training mode can improve the leg support strength of jumpers. This paper suggests that high jump athletes can further adopt this lower limb strength training method. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

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Section: Resultsmentioning

confidence: 99%

Isokinetic Kneel Muscle Strength Characteristics in High Jump Athletes

2023

Rev Bras Med Esporte

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“…Another unique method by which CMJs and SLJs may be assessed is by examining the efficiency of the force-time signal (12,26), which involves examining the peak force of the force-time signal relative to the low position of the countermovement. In Division I NCAA athletes, McHugh et al (26) suggested that peak force occurring at the bottom of the countermovement may yield superior eccentric (unweighting and braking phase) and performance metrics than when peak force does not occur at the bottom of the countermovement.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies (12,26) have stated that if the force at the low position of the countermovement is within 1% of the peak force, then the jump is considered more biomechanically efficient. Therefore, an efficiency index was calculated for each jump using the following equation (12,26): (peak force − force at the low position)/peak force. This metric was used to determine the efficiency of the vertical jumps (i.e., closer to 0.01 [1%]) before and after the strength and conditioning program.…”

Section: Methodsmentioning

confidence: 99%

“…For example, previous studies demonstrated that metrics calculated during the eccentric phase may be influenced by sport training (7,22,27), muscle strength (10), and the design of the training program (19,24). In addition, previous studies have showed that improvements in metrics calculated during the eccentric portions of the CMJ may contribute to subsequent improvements during the concentric portion (1,5,10,13,22,26,29). Not only this, but in NCAA Division I athletes and youth athletes, previous studies (12,26) suggested that practitioners may be able to monitor changes in the CMJs efficiency by assessing force production relative to the countermovement depth of the jump.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, previous studies have showed that improvements in metrics calculated during the eccentric portions of the CMJ may contribute to subsequent improvements during the concentric portion (1,5,10,13,22,26,29). Not only this, but in NCAA Division I athletes and youth athletes, previous studies (12,26) suggested that practitioners may be able to monitor changes in the CMJs efficiency by assessing force production relative to the countermovement depth of the jump. Theoretically, the countermovement can be modeled as a spring, with eccentric stiffness being analogous to compressing the spring.…”

Section: Introductionmentioning

confidence: 99%

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Effects of a Strength and Conditioning Offseason Program on Countermovement Jump Ground Reaction Forces in Division I American Football Players

Gillen,

Burch,

Saucier

et al. 2023

Journal of Strength &Amp; Conditioning Research

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Gillen, ZM, Burch, RF, Saucier, DN, Strawderman, L, Luczak, T, Piroli, A, Petway, AJ, and Rath, T. Effects of a strength and conditioning offseason program on countermovement jump ground reaction forces in Division I American football players. J Strength Cond Res XX(X): 000–000, 2023—The purpose of this study was to examine the effects of a 10-week strength and conditioning offseason program on the ground reaction forces (GRFs) of American football players during single-leg and double-leg countermovement jumps (SLJ and CMJ, respectively). Each subject visited the laboratory twice, once for preoffseason and once for postoffseason testing. During each visit, subjects performed CMJs and SLJs for each leg. Ground reaction forces were collected by force plates to quantify unweighting, braking, propulsive, and performance metrics for each jump. In addition, an efficiency index was calculated for each jump to examine changes in vertical jump efficiency. Dependent samples t tests compared all CMJ metrics. Two-way repeated measures analyses of variance (leg × time) compared all SLJ metrics. An alpha level of p ≤ 0.05 was considered statistically significant. For the CMJ, propulsive phase duration decreased due to the program (p = 0.007), whereas peak braking power, peak propulsive power, mean propulsive force, and jump height increased (p ≤ 0.012). For the SLJ, peak braking power, force at the low position, braking rate of force development, eccentric force, peak propulsive power, mean propulsive force, and jump height increased in both legs (p ≤ 0.044). The efficiency index increased for the CMJ and the SLJ for both legs (p ≤ 0.016). This study demonstrated that SLJ and CMJ vertical jump performance significantly increases in as few as 10 weeks of offseason strength and conditioning. Strength and conditioning programming may effectively increase vertical jump performance, as assessed by GRFs, which can be used as a simple indicator regarding changes in athletic performance.

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Building for the Future: A Systematic Review of the Effects of Eccentric Resistance Training on Measures of Physical Performance in Youth Athletes

Bright

Handford

Mundy³

et al. 2023

Sports Med

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Background Eccentric resistance training is recognised as an effective stimulus for enhancing measures of muscular strength and power in adult populations; however, its value in youth athletes is currently not well understood. Objective The aim of this systematic review was to critically appraise the effects of eccentric resistance training on measures of physical performance (i.e. muscular strength, jump, sprint and change of direction) in youth athletes 18 years of age and under. Methods Original journal articles published between 1950 and June 2022 were retrieved from electronic search engines of PubMed, SPORTDiscus and Google Scholar’s advanced search option. Full journal articles investigating the acute and chronic effects of eccentric resistance training on measures of physical performance in youth athletes (i.e. a person 18 years of age or under who competes in sport) were included. The methodological quality and bias of each study were assessed prior to data extraction using a modified Downs and Black checklist. Results The search yielded 749 studies, of which 436 were duplicates. Three-hundred studies were excluded based upon title and abstract review and a further 5 studies were removed following the modified Downs and Black checklist. An additional 14 studies were identified during backward screening. Accordingly, 22 studies were included in our systematic review. The Nordic hamstring exercise and flywheel inertial training were the most frequently used eccentric resistance training methods in youth athletes. Improvements in physical performance following the Nordic hamstring exercise are dependent upon an increase in the breakpoint angle, rather than training volume (sets and repetitions), and are further elevated with the addition of hip extension exercises or high-speed running. A minimum of 3 familiarisation trials is necessary to elicit meaningful adaptations following flywheel inertial training. Furthermore, an emphasis should be placed upon decelerating the rotating flywheel during the final one to two thirds of the eccentric phase, rather than gradually throughout the entire eccentric phase. Conclusions The findings of this systematic review support the inclusion of eccentric resistance training in youth athletes to improve measures of muscular strength, jump, sprint and change of direction performance. The current eccentric resistance training methods are predominantly limited to the Nordic hamstring exercise and flywheel inertial training; however, the efficacy of accentuated eccentric loading to improve jump performance warrants attention in future investigations.

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Comparisons of countermovement jump force profiles in youth athletes

Cited by 5 publications

References 42 publications

Isokinetic Kneel Muscle Strength Characteristics in High Jump Athletes

Isokinetic Kneel Muscle Strength Characteristics in High Jump Athletes

Effects of a Strength and Conditioning Offseason Program on Countermovement Jump Ground Reaction Forces in Division I American Football Players

Building for the Future: A Systematic Review of the Effects of Eccentric Resistance Training on Measures of Physical Performance in Youth Athletes

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