Multiarticular isokinetic high-load eccentric training induces large increases in eccentric and concentric strength and jumping performance

A Systematic Review of Flywheel Training Effectiveness and Application on Sport Specific Performances

The objective of this systematic review was to examine the effectiveness of flywheel training, which allows for the replication of specific sports movements, overloading both the concentric and eccentric phases. Inclusion criteria were injury prevention outcomes; ability in terms of strength, power, sprinting, jumping and change of direction; competitive athletes; and RCTs. Exclusion criteria were a lack of a control group and lack of baseline and/or follow-up data. The databases used were Web of Science, Scopus, PubMed, Cochrane Library, and Sage. The revised Cochrane risk-of-bias tool was used to assess the quality of the selected RCTs. The Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence was used. A PICOS (participants, intervention, comparators, study outcomes, and study design) approach was used to evaluate eligibility. A total of 21 RCTs with 8 to 54 participants in each study analyzed flywheel technology and its application in nine sports. The results showed that flywheel training is a good strategy to improve sports performance, providing variation in training methodologies and athletes’ adherence. Further studies are needed to define guidelines on training modality, weekly frequency, volume, and inertia load. Only a few studies have applied the flywheel device directly to overload specific multidirectional movements at different joint angles. This method is not exempt from criticalities, such as the cost and the ability to carry out only individual training.

Transfer Effects of a Multiple-Joint Isokinetic Eccentric Resistance Training Intervention to Nontraining-Specific Traditional Muscle Strength Measures

Relatively few investigations have examined the transfer effects of multiple-joint isokinetic eccentric only (MJIE) resistance training on non-specific measures of muscle strength. This study investigated the transfer effects of a short-term MJIE leg press (Eccentron) resistance training program on several non-specific measures of lower-body strength. Fifteen participants performed Eccentron training three times/week for four weeks and were evaluated on training-specific Eccentron peak force (EccPF), nontraining-specific leg press DCER one-repetition maximum (LP 1 RM), and peak torques of the knee extensors during isokinetic eccentric (Ecc30), isokinetic concentric (Con150) and isometric (IsomPT) tasks before and after the training period. The training elicited a large improvement in EccPF (37.9%; Cohen's d effect size [ES] = 0.86). A moderate transfer effect was observed on LP 1 RM gains (19.0%; ES = 0.48) with the magnitude of the strength improvement being about one-half that of EccPF. A small effect was observed on IsomPT and Ecc30 (ES = 0.29 and 0.20, respectively), however, pre-post changes of these measures were not significant. Con150 testing showed no effect (ES = 0.04). These results suggest a short term MJIE training program elicits a large strength improvement in training-specific measures, a moderate strength gain transfer effect to DCER concentric-based strength of a similar movement (i.e., LP 1 RM), and poor transfer to single-joint knee extension measures.

The effectiveness of different ankle strengthening training programs on performance

BACKGROUND

The purpose of this study was to investigate the effectiveness of different ankle strengthening training programs: eccentric, concentric, and resistance bands, on performance of university level sedentary males.

METHODS

Sixty-three males between the ages of 18 and 26 years were randomized to either eccentric isokinetic (n=21), concentric isokinetic (n=21), and resistance bands ankle strengthening groups (n=21). Training was performed three days a week, for eight weeks for both sides of ankle. Each program was made progressively harder by increasing the number of repetitions or sets. Measurements evaluating strength, balance and jumping performance were repeated pre, post and at one month (follow-up) after training.

RESULTS

Statistical significance was observed for concentric evertor strength for both sides of the ankle for all groups after training (p<0.05). In addition, statistically significant increases were seen in jumping performance for all groups and dynamic balance for eccentric and concentric groups (p<0.05), with the concentric being statistically higher compared to the resistance bands group for all parameters (p<0.05).

CONCLUSIONS

Ankle isokinetic strength (eccentric, concentric) training is more effective than resistance bands regarding improvement on strength, explosive strength, and dynamic balance. Ankle isokinetic strength training, which includes evertor and invertor muscles, improves performance, especially when applied concentrically. Therefore, the proper strengthening of ankle muscles will prevent the re-injury of ankles with individuals returning to activities.

Multiple-Joint Isokinetic Dynamometry: A Critical Review

Dvir, Z and Müller, S. Multiple-joint isokinetic dynamometry: a critical review. J Strength Cond Res 34(2): 587-601, 2020-Angular isokinetic dynamometry (AID) is widely regarded as the gold standard for dynamic muscle performance testing. Based on the rotational movement of its actuator, AID targets "single-joint" (knee, shoulder, hip, etc.) configurations namely measurement of muscle potential while it moves the lever arm-limb assembly ostensibly around a single fixed axis. On the other hand, the application of multiple-joint isokinetic dynamometry (MID) is relatively narrow, both in research and in practice. This situation is due, possibly, to the fact that these dynamometers are generally more limited in scope namely to testing/conditioning of combined hip, knee, ankle motion (leg press), combined shoulder, elbow motion, and lifting motion patterns, despite the fact that all 3 are associated with higher functionality. However, with the emerging importance of MID, this critical review takes a fresh look at its various aspects including the terminology and classification of multiple-joint isokinetic dynamometers; the problem of scaling namely the need to adjust the range of motion and linear velocities to subjective anthropometric measures; specific technical and methodological issues that underlie the valid application of these dynamometers; available reference values; and the reproducibility of MID-based test findings. Analysis of these topics indicates that MID may validly and effectively be applied for the assessment and conditioning of specific muscle action patterns. However, there is a clear need for standardization of tests and for conditioning protocols alongside research into the use of this method in various clinical cohorts.

Eccentric Resistance Training in Youth: Perspectives for Long-Term Athletic Development

The purpose of this narrative review is to discuss the role of eccentric resistance training in youth and how this training modality can be utilized within long-term physical development. Current literature on responses to eccentric exercise in youth has demonstrated that potential concerns, such as fatigue and muscle damage, compared to adults are not supported. Considering the importance of resistance training for youth athletes and the benefits of eccentric training in enhancing strength, power, speed, and resistance to injury, its inclusion throughout youth may be warranted. In this review we provide a brief overview of the physiological responses to exercise in youth with specific reference to the different responses to eccentric resistance training between children, adolescents, and adults. Thereafter, we discuss the importance of ensuring that force absorption qualities are trained throughout youth and how these may be influenced by growth and maturation. In particular, we propose practical methods on how eccentric resistance training methods can be implemented in youth via the inclusion of efficient landing mechanics, eccentric hamstrings strengthening and flywheel inertia training. This article proposes that the use of eccentric resistance training in youth should be considered a necessity to help develop both physical qualities that underpin sporting performance, as well as reducing injury risk. However, as with any other training modality implemented within youth, careful consideration should be given in accordance with an individual's maturity status, training history and technical competency as well as being underpinned by current long-term physical development guidelines.

Eccentric Training Interventions and Team Sport Athletes

Eccentric resistance training has been shown to improve performance outcomes in a range of populations, making it a popular choice for practitioners. Evidence suggests that neuromuscular adaptations resulting from eccentric overload (EO) and accentuated eccentric loading (AEL) methods could benefit athletic populations competing in team sports. The purpose of this review was to determine the effects of eccentric resistance training on performance qualities in trained male team sport athletes. A systematic review was conducted using electronic databases PubMed, SPORTDiscus and Web of Science in May 2019. The literature search resulted in 1402 initial articles, with 14 included in the final analysis. Variables related to strength, speed, power and change of direction ability were extracted and effect sizes were calculated with a correction for small sample size. Trivial, moderate and large effect sizes were reported for strength (-0.17 to 1.67), speed (-0.08 to 1.06), power (0.27 to 1.63) and change of direction (0.48 to 1.46) outcomes. Eccentric resistance training appears to be an effective stimulus for developing neuromuscular qualities in trained male team sport athletes. However, the range of effect sizes, testing protocols and training interventions suggest that more research is needed to better implement this type of training in athletic populations.

Isokinetic resistance training combined with eccentric overload improves athletic performance and induces muscle hypertrophy in young ice hockey players

OBJECTIVES

To determine the combined effects of slow isokinetic resistance training and eccentric overload and compare it to traditional resistance training on strength, power, body composition and muscle hypertrophy in young ice hockey players.

DESIGN

Experimental, randomized trial.

METHODS

Twenty-two resistance-trained ice hockey players (18±1year) were assigned to either isokinetic resistance training and eccentric overload (ISO/ECC; n=11) or traditional resistance training (TRAD; n=11). Participants underwent supervised progressive resistance training for 8 weeks (2-3 sessions/week) involving lower body multiple-joint exercises (heavy squats and explosive jump squats). The ISO/ECC group performed their training using a computerized robotic engine system (1080 Quantum synchro, Sweden), whereas the TRAD group performed the same resistance exercises with isotonic loading. Before and after the intervention, participants were evaluated in 1RM back squat, loaded jump squats, sprint- and jump performance, body composition and muscle thickness using ultrasound measurement.

RESULTS

Similar moderate increases in 1RM back squat and power output in the jump squats were found in both the ISO/ECC and TRAD groups (11-17%, P<0.01), whereas only the ISO/ECC group showed improvements in drop jump performance (9.8%, P=0.01). Moreover, similar trivial changes in body composition were observed in both groups, while only the ISO/ECC training group increased muscle thickness in the vastus intermedius (P=0.01) and rectus femoris muscles (P=0.03).

CONCLUSIONS

Both modalities effectively increased maximal strength and power output, whereas isokinetic resistance training, combined with eccentric overload, improved drop jump performance and induced greater muscle hypertrophy than traditional training in young ice hockey players.

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.

Chronic Adaptations to Eccentric Training: A Systematic Review

BACKGROUND

Resistance training is an integral component of physical preparation for athletes. A growing body of evidence indicates that eccentric strength training methods induce novel stimuli for neuromuscular adaptations.

OBJECTIVE

The purpose of this systematic review was to determine the effects of eccentric training in comparison to concentric-only or traditional (i.e. constrained by concentric strength) resistance training.

METHODS

Searches were performed using the electronic databases MEDLINE via EBSCO, PubMed and SPORTDiscus via EBSCO. Full journal articles investigating the long-term (≥4 weeks) effects of eccentric training in healthy (absence of injury or illness during the 4 weeks preceding the training intervention), adult (17-35 years), human participants were selected for the systematic review. A total of 40 studies conformed to these criteria.

RESULTS

Eccentric training elicits greater improvements in muscle strength, although in a largely mode-specific manner. Superior enhancements in power and stretch-shortening cycle (SSC) function have also been reported. Eccentric training is at least as effective as other modalities in increasing muscle cross-sectional area (CSA), while the pattern of hypertrophy appears nuanced and increased CSA may occur longitudinally within muscle (i.e. the addition of sarcomeres in series). There appears to be a preferential increase in the size of type II muscle fibres and the potential to exert a unique effect upon fibre type transitions. Qualitative and quantitative changes in tendon tissue that may be related to the magnitude of strain imposed have also been reported with eccentric training.

CONCLUSIONS

Eccentric training is a potent stimulus for enhancements in muscle mechanical function, and muscle-tendon unit (MTU) morphological and architectural adaptations. The inclusion of eccentric loads not constrained by concentric strength appears to be superior to traditional resistance training in improving variables associated with strength, power and speed performance.