Velocity-Load Jump Testing Predicts Acceleration Performance in Elite Speed Skaters: But Does Movement Specificity Matter?

PURPOSE

In this study, we compared the influence of movement specificity during velocity-load jump testing to predict on-ice acceleration performance in elite speed skaters.

METHODS

Elite long-track speed skaters (N = 27) performed velocity-load testing with 3 external loads during unilateral horizontal jumping, lateral jumping, and bilateral vertical countermovement jumping. For the unilateral tests, external load conditions were set to 10 N, 7.5% and 15% of external load relative to body weight. For the countermovement jumping, load conditions were body weight and 30% and 60% of external load relative to body weight. On-ice performance measures were obtained during maximal 50-m accelerations from a standing start, including maximal skating speed, maximal acceleration capacity, and maximum horizontal power. The 100-m split time from a 500-m race was also obtained. Regularized regression models were used to identify the most important predictors of on-ice acceleration performance. In addition to regularized regression coefficients, Pearson correlation coefficients (r) were calculated for all variables retained by the model to assess interrelationships between single predictors and on-ice performance measures.

RESULTS

The countermovement jump with 30% of body mass demonstrated the strongest association with maximal skating speed, maximum horizontal power, and 100-m time (regularized regression coefficient = .16-.49, r = .84-.97, P < .001). Horizontal jump with 15% of body mass was the strongest predictor of maximal acceleration capacity performance (regularized regression coefficient = .08, r = .83, P < .001).

CONCLUSIONS

The findings of this study suggest that mechanical specificity rather than movement specificity was more relevant for predicting on-ice acceleration performance.

The impact of landing forces on repeated jumping performance

BACKGROUND

High-velocity concentric actions can be negatively impacted by cumulative fatigue during plyometric training. Reducing vertical ground reaction forces (GRF) upon landing could decrease eccentric demands, potentially minimizing fatigue, maintaining concentric performance, and benefiting concentric training adaptations. Therefore, this study examined the effect of intentionally higher and lower landing vertical GRF on the ability to sustain concentric jumping performance.

METHODS

Twenty men (25.2±3.5 years) performed 30 maximal effort jumps over a 50 cm hurdle (high-landing GRF) and onto a 50 cm box (low-landing GRF), on two separate occasions in a counter-balanced order. Jumps were measured using two force platforms (one for takeoff and one for landing) and a linear position transducer. The 30 jumps were divided into 5 groups of 6 repetitions, and the mean value for each group was analyzed.

RESULTS

There was no significant condition × repetition group interaction for any parameters, indicating that the greater landing GRF during hurdle jumps did not negatively affect concentric jump performance throughout the 30 jumps. Concentric velocities and jump height were significantly greater during box jumps compared to hurdle jumps.

CONCLUSIONS

Thirty maximal-effort jumps did not cause fatigue-related decrease of performance, independent of jump type (i.e., the magnitude of landing GRF). Although, reduced vertical GRF upon landing appears to have a neutral-to-positive effect on concentric jumping performance. Therefore, reducing landing GRF, such as by using BJs, could acutely augment jumping performance and help to reduce cumulative training load.

Kinetic and Kinematic Assessment of the Band-Assisted Countermovement Jump

ABSTRACT

Fernandes, JFT, Arede, J, Clarke, H, Garcia-Ramos, A, Perez-Castilla, A, Norris, JP, Wilkins, CA, and Dingley, AF. Kinetic and kinematic assessment of the band-assisted countermovement jump. J Strength Cond Res XX(X): 000-000, 2022-This study sought to elucidate kinetic and kinematic differences between unloaded and band-assisted countermovement jumps (CMJs). In a randomized order, 20 healthy subjects (mass 84.5 ± 18.6 kg) completed 3 repetitions of CMJs across 3 conditions: unloaded (at body mass), low, and moderate band (8.4 ± 1.9 and 13.3 ± 3.3 kg body weight reduction, respectively). For all repetitions, a force platform and linear position transducer were used to record and calculate kinetic and kinematic data. Body weight was significantly different between the unloaded, low, and moderate band conditions (p < 0.05). Peak velocity, absolute peak, and mean force and movement duration displayed a trend that was mostly related to the condition (i.e., unloaded > low > moderate) (p < 0.05). The opposing trend (i.e., moderate > low > unloaded) was generally observed for relative peak and mean force, reactive strength index modified, and flight time (p < 0.05). No differences were observed for mean velocity, movement duration, and absolute and relative landing forces (p > 0.05). The use of band assistance during CMJs can alter force, time, and velocity variables. Practitioners should be aware of the potential positive and negative effects of band assistance during CMJs.

Multidisciplinary Neuromuscular and Endurance Interventions on Youth Basketball Players: A Systematic Review with Meta-Analysis and Meta-Regression

The main aims of this systematic review with meta-analysis and meta-regression were to describe the effect of multidisciplinary neuromuscular and endurance interventions, including plyometric training, mixed strength and conditioning, HIIT basketball programs and repeated sprint training on youth basketball players considering age, competitive level, gender and the type of the intervention performed to explore a predictive model through a meta-regression analysis. A structured search was conducted following PRISMA guidelines and PICOS model in Medline (PubMed), Web of Science (WOS) and Cochrane databases. Groups of experiments were created according to neuromuscular power (vertical; NPV and horizontal; NPH) and endurance (E). Meta-analysis and sub-groups analysis were performed using a random effect model and pooled standardized mean differences (SMD). A random effects meta-regression was performed regressing SMD for the different sub-groups against percentage change for NPV and NPH. There was a significant positive overall effect of the multidisciplinary interventions on NPV, NPH and E. Sub-groups analysis indicate differences in the effects of the interventions on NPV and NPH considering age, gender, competitive level and the type of the intervention used. Considering the current data available, the meta-regression analysis suggests a good predictability of U-16 and plyometric training on jump performance. Besides, male and elite level youth basketball players had a good predictability on multidirectional speed and agility performance.

The effects of joint hypermobility syndrome on the kinematics and kinetics of the vertical jump test

PURPOSE

Biomechanical impairments are not apparent during walking in people with Joint Hypermobility Syndrome (JHS). This research explored biomechanical alterations during a higher intensity task, vertical jumping.

MATERIALS AND METHODS

This cross-sectional study compared a JHS group (n = 29) to a healthy control group (n = 30). Joint kinematics and kinetics were recorded using a Qualisys motion capture system synchronized with a Kistler platform. Independent sample t-tests and standardised mean differences (SMD) were used for statistical analysis.

RESULTS

No significant statistical or clinical differences were found between groups in joint kinematics and jump height (p ≥ 0.01). Sagittal hip and knee peak power generation were statistically lower in the JHS group during the compression phase (p ≤ 0.01), but not clinically relevant (SMD < 0.5). Clinically relevant reductions were found in the JHS group knee and ankle peak moments during the compression phase, and hip and knee peak power generation during the push phase (SMD ≥ 0.5), although these were not statistically significant (p ≥ 0.01).

CONCLUSION

The JHS group achieved a similar jump height but with some biomechanical alterations. Further understanding of the joint biomechanical behavior could help to optimize management strategies for JHS, potentially focusing on neuromuscular control and strength/power training.

Assisted Jumping in Healthy Older Adults: Optimizing High-Velocity Training Prescription

Tufano, JJ, Vetrovsky, T, Stastny, P, Steffl, M, Malecek, J, and Omcirk, D. Assisted jumping in healthy older adults: optimizing high-velocity training prescription. J Strength Cond Res XX(X): 000-000, 2020-Because older adults benefit from power training, training strategies for athletes such as supramaximal velocity-assisted jumping could also be useful for older adults. However, optimizing-assisted exercise prescription in older adults remains uninvestigated. Therefore, the purpose of this study was to determine the effects of different bodyweight (BW) assistance levels on jumping force and velocity in healthy older adults. Twenty-three healthy older adults (67.6 ± 7.6 years, 167.0 ± 8.8 cm, 72.7 ± 14.3 kg, and 27.1 ± 6.9% body fat) performed 5 individual countermovement jumps at BW, 90, 80, 70, and 60% of BW. Jumps were performed on a force plate, which provided peak take-off force (TOF), flight time, and peak impact force. A linear position transducer measured peak concentric velocity (PV). The rating of perceived exertion (RPE) was also assessed after each condition. Take-off force was greater during BW than all other conditions, 90 and 80% were greater than 70 and 60%, but there were no differences between 80 and 90% or between 70 and 60%. The FT progressively increased at all assistance levels, and PV was faster for all assistance levels than BW, with no differences between assistance levels. Impact force was greater during BW than 80, 70, and 60% and was greater during 90% than 60%. The RPE was less than BW during all assistance conditions but was the least during 70%. Implementing assisted jumping between 70 and 80% of BW in older adults likely provides the ideal combination of force, velocity, and RPE.

Assisted jumping: A possible method of incorporating high-velocity exercise in older populations

In the past, older adults were traditionally deemed too weak or fragile to participate in high-intensity exercise, but more recent research indicates that not only is high-intensity exercise not dangerous in this population, but it may in fact be a preferable form of exercise over other, less-intense alternatives. However, many seniors still do not participate in high-intensity exercise despite the mounting evidence that it can improve a number of physiological functions and ultimately increase quality of life. As health, sport, and medical professionals, we must continuously ask ourselves how we can apply our lab-based findings in real-life scenarios, and in the case of older adults, we must find a way to circumvent some of their most common reasons for not exercising, which can include a lack of time, a lack of know-how, a lack of motivation, a fear that high-intensity exercise is unsafe, and a perception that high-intensity exercise is too difficult. Therefore, introducing quick, simple, safe, and perceptually easy exercises may result in immediate health and functional benefits and may serve as a gateway exercise to usher older adults into the realm of high-intensity training. Specifically, assisted jumping could serve this purpose. In this article, the ideas behind the theory and practice of assisted jumping are set forth, providing an evidence-based hypothesis from which future researchers can build on to implement high-speed, high-power, high-intensity exercise in older populations in both research and practical settings.

Field-Based and Lab-Based Assisted Jumping: Unveiling the Testing and Training Implications

Purpose: Assisted jumping can supplement resistance training and traditional plyometric training to increase vertical jump performance. However, as coaches may choose to make field-based decisions based on lab-based research, this study determined whether a field-based assisted jumping set-up results in different ground contact times (CT), take off forces (TOF), flight times (FT), and impact forces (IF) compared to a lab-based set-up.

Methods: Eighteen active males (24.8 ± 3.0 yr; 178.8 ± 7.8 cm; 77.8 ± 7.8 kg) performed two sessions of assisted jumping: one with each hand holding a commercially available resistance band (1m) that was attached to a pull-up bar (_FIELD), and the other with assistance from a custom-built system of ropes, pulleys, and long (3 m) elastic bands (_LAB). With each set-up, subjects performed five sets of five countermovement jumps on a force plate. Each set was performed with either bodyweight (BW), 90, 80, 70, or 60% of BW, which was achieved by either grabbing higher or lower on the bands during _FIELD, or by being pulled upward via a full-body harness during _LAB. The order of each visit was counter-balanced, and the order of jumps within each visit was quasi-randomized. Data from the 90, 80, 70, and 60% trials for each set-up were then expressed relative to the data of BW jumps, and these relative values were then used for analysis.

Results: CT_FIELD was less than CT_LAB at 80, 70, and 60%. FT_FIELD was greater than FT_LAB at 90 and 80%, but FT_LAB became greater at 60%. TOF and IF remained unchanged during _LAB, but TOF_FIELD was consistently less than TOF during BW, with IF_FIELD generally being greater than IF_LAB.

Conclusion: If the purpose of assisted jumping is to spend less time on the ground without decreasing force, systems with finite adjustments and longer bands like _LAB should be used. However, shorter bands similar to _FIELD may also be used; but due to the larger variability of assistance throughout the range of motion, such systems may alter the neuromuscular characteristics of the jump in other ways that should be investigated in future research.

Validity and Reliability of Jump Height Measurements Obtained From Nonathletic Populations With the VERT Device

BACKGROUND AND PURPOSE

Vertical jump (VJ) is commonly used to assess lower extremity power in athletic populations. A portable device called the VERT has been validated for this population, but not in nonathletic populations. We sought in this study to assess the clinimetric properties of VJ height measurements obtained with the VERT from older and younger nonathletes.

METHODS

Twenty-eight participants (14 older, 14 younger, evenly split between male and female) completed 2 submaximal and 3 maximal VJ trials wearing the VERT during 2 sessions separated by 5 to 9 days. During the first session, their VJ heights were also monitored using motion capture video.

RESULTS

Analysis revealed concurrent validity of the VERT against motion capture (intraclass correlation coefficient [ICC3,1] = 0.826-0.950) and known-groups validity of the VERT based on age and gender (P < .001). Strong parallel reliability against a second VERT device (ICC = 0.992) was demonstrated as was strong test-retest reliability (ICC = 0.968).

CONCLUSIONS

The VERT device provides valid and reliable measures of VJ height in nonathletic populations, including older adults. However, the VERT may not be suitable for recording the low jump heights of some older adults.

Developing a measure of muscular power during a functional task for older adults

Background

Muscular power is an important aspect of many activities of daily living and declines at a faster rate than other fitness parameters (i.e. muscular strength and endurance). Assessing muscular power among older adults is problematic as many of the popular tests are contraindicated among older adults and field tests to assess muscular power among older adults have not been validated among older adults. Therefore, the aim of the present investigation was to determine the validity and reliability of a field test to measure of muscular power during a functional movement among community-dwelling older adults (≥ 65 years).

Methods

Twenty community-dwelling older adults (71.6 ± 5.6) volunteered to have their muscular power assessed during repeated sit-to-stand (STS) tasks. Each participant performed 10 STS with 60 s rest between trials. Muscular power was assessed during this functional movement with the Tendo as well as change in center of mass (COM) over time using cinematography.

Results

Relative power measured by Tendo was 5.34 ± 1.67 W/kg and values for COM were 5.39 ± 1.73 W/kg (p = .86). Cronbach’s alpha for Tendo muscular power for repeated trials was .98.

Conclusions

Tendo is a simple field method of determining muscular power among older adults and validation is essential. Results from this investigation support Tendo as a valid and reliable method for determining muscular power during a STS task among older adults. Clinicians may use this tool to evaluate and assess progress in older adults’ power and physical functioning.