The functional effect of a distal rectus femoris tenotomy in adults with cerebral palsy

The purpose of this study was to determine the effect of a distal rectus femoris tenotomy on function and gait in adults with cerebral palsy who had diminished knee flexion during swing. A stiff knee gait pattern is commonly seen in individuals with cerebral palsy and frequently leads to tripping and falling. Five subjects, 25–51 years, (34.6 ± 10.3 years) participated in the study; each individual had the surgery after the age of 18. Four of the five subjects underwent bilateral distal rectus femoris tenotomies for a total of nine limbs being studied. Four of the five subjects had a single procedure of a distal rectus femoris tenotomy and one subject also had bilateral adductor tenotomies. All individuals underwent a pre-operative and post-operative, (3.28 ± 1.6 years) three-dimensional gait analysis. Pre-operative gait revealed diminished peak knee flexion and out of phase rectus femoris activity with a quiet vastus lateralis during swing in all subjects. Significant findings after a distal rectus femoris tenotomy included: improved peak swing knee flexion, improved peak stance hip extension, and increased total knee excursion without loss in knee extension strength. During swing, knee flexion angle improved on average 11° which correlated with subjective report of less shoe wear, tripping, and falling due to improved clearance. In conclusion, a distal rectus femoris tenotomy should be considered a surgical option for adults with cerebral palsy and a stiff knee gait pattern to improve mobility, function, and quality of life.     

Time-dependent directional intermuscular coherence analysis reveals that forward and backward arm swing equally drive the upper leg muscles during gait initiation

BackgroundHuman bipedal gait benefits from arm swing, as it drives and shapes lower limb muscle activity in healthy participants as well as patients suffering from neurological impairment. Also during gait initiation, arm swing instructions were found to facilitate leg muscle recruitment.Research questionThe aim of the present study is to exploit the directional decomposition of coherence to examine to what extent forward and backward arm swing contribute to leg muscle recruitment during gait initiation.MethodsAmbulant electromyography (EMG) from shoulder muscles (deltoideus anterior and posterior) and upper leg muscles (biceps femoris and rectus femoris) was analysed during gait initiation in nineteen healthy participants (median age of 67 ± 12 (IQR) years). To assess to what extent either deltoideus anterior or posterior muscles were able to drive upper leg muscle activity during distinct stages of the gait initiation process, time dependent intermuscular coherence was decomposed into directional components based on their time lag (i.e. forward, reverse and zero-lag).ResultsCoherence from the forward directed components, representing shoulder muscle signals leading leg muscle signals, revealed that deltoideus anterior (i.e. forward arm swing) and deltoideus posterior (i.e. backward arm swing) equally drive upper leg muscle activity during the gait initiation process.SignificanceThe presently demonstrated time dependent directional intermuscular coherence analysis could be of use for future studies examining directional coupling between muscles or brain areas relative to certain gait (or other time) events. In the present study, this analysis provided neural underpinning that both forward and backward arm swing can provide neuronal support for leg muscle recruitment during gait initiation and can therefore both serve as an effective gait rehabilitation method in patients with gait initiation difficulties.     

Effects of 4-week slackline training on lower limb joint motion and muscle activation

ObjectivesTo investigate the effects of four weeks of slacklining on lower limb kinematics and muscle activity following a slip of the upright stance.DesignA randomized, gender matched study.MethodsTwenty-four young healthy adults participated in the study and were assigned to either a training or a control group. The training group completed a 4-week training program on slacklines, while the control group received no slackline training. Before and after training, participants performed single leg standing tasks on a moveable platform. During medio-lateral platform perturbation, platform displacement, lower limb joint motion (ankle, knee and hip) and surface electromyography (EMG) measurements from six lower limb muscles were recorded.ResultsIn the training group, a decrease in platform mean and maximum velocity (all p < 0.05) was detected, but no changes were observed for the release time and maximum deflection (all p > 0.05) of the platform. Regarding lower limb kinematics, a reduced corrective action was detected in the knee joint (p < 0.05), whereas only a trend towards a decrease could be observed in the ankle joint (p < 0.1). EMG data revealed an enhanced activation of the rectus femoris (p < 0.05), as well as a trend to increased rectus femoris to biceps femoris co-activation (p = 0.06) in the preparatory phase for training group.ConclusionsThe data strongly support that slacklining can improve postural control and enhance functional knee joint stability, which seems to be induced by enhanced preparatory muscle activation of the rectus femoris.     

Electromyographic timing analysis of forward and backward cycling

PURPOSE: Backward walking to running progressions are becoming a popular, nontraditional component of functional knee rehabilitation programs. The purpose of this electromyographic (EMG) and motion analysis study was to compare the activation duration of the vastus medialis, vastus lateralis, rectus femoris, medial hamstrings, lateral hamstring, tibialis anterior, and gastrocnemius muscles during forward and backward cycling. We hypothesized that the hamstrings would demonstrate greater activation duration during backward cycling. METHODS: The right lower extremity of 12 healthy subjects (6 male and 6 female) was instrumented with surface EMG electrodes and retroreflective markers to confirm lower extremity kinematic consistency between conditions. RESULTS: Statistical analysis of hip, knee, and ankle kinematics (200 Hz sampling rate) and gender failed to reveal significant differences between conditions (P > 0.05). Quadrant analysis of muscle activation duration with Bonferroni corrections for multiple comparisons revealed that medial and lateral hamstring activation duration was greater during the early recovery phase (quadrant III) of backward cycling than forward cycling (P < 0.00156). Rectus femoris activation duration was greater in the early propulsive phase of backward cycling (quadrant 1) (P < 0.00156) and in the early recovery phase of forward cycling (quadrant III) (P < 0.00156). CONCLUSIONS: These findings lend support for the use of backward cycling during the early recovery phase (quadrant III) to achieve a selective hamstring muscle response of relatively decreased patellofemoral stress and anterior cruciate ligament strain.     

In-shoe plantar pressure measurements for the evaluation and adaptation of foot orthoses in patients with rheumatoid arthritis: A proof of concept study

ObjectivesImproving foot orthoses (FOs) in patients with rheumatoid arthritis (RA) by using in-shoe plantar pressure measurements seems promising. The objectives of this study were to evaluate (1) the outcome on plantar pressure distribution of FOs that were adapted using in-shoe plantar pressure measurements according to a protocol and (2) the protocol feasibility.MethodsForty-five RA patients with foot problems were included in this observational proof-of concept study. FOs were custom-made by a podiatrist according to usual care. Regions of Interest (ROIs) for plantar pressure reduction were selected. According to a protocol, usual care FOs were evaluated using in-shoe plantar pressure measurements and, if necessary, adapted. Plantar pressure–time integrals at the ROIs were compared between the following conditions: (1) no-FO versus usual care FO and (2) usual care FO versus adapted FO. Semi-structured interviews were held with patients and podiatrists to evaluate the feasibility of the protocol.ResultsAdapted FOs were developed in 70% of the patients. In these patients, usual care FOs showed a mean 9% reduction in pressure–time integral at forefoot ROIs compared to no-FOs (p = 0.01). FO adaptation led to an additional mean 3% reduction in pressure–time integral (p = 0.05). The protocol was considered feasible by patients. Podiatrists considered the protocol more useful to achieve individual rather than general treatment goals. A final protocol was proposed.ConclusionsUsing in-shoe plantar pressure measurements for adapting foot orthoses for patients with RA leads to a small additional plantar pressure reduction in the forefoot. Further research on the clinical relevance of this outcome is required.     

Surface-EMG analysis for the quantification of thigh muscle dynamic co-contractions during normal gait

The research purpose was to quantify the co-contraction patterns of quadriceps femoris (QF) vs. hamstring muscles during free walking, in terms of onset-offset muscular activation, excitation intensity, and occurrence frequency. Statistical gait analysis was performed on surface-EMG signals from vastus lateralis (VL), rectus femoris (RF), and medial hamstrings (MH), in 16315 strides walked by 30 healthy young adults. Results showed full superimpositions of MH with both VL and RF activity from terminal swing, 80 to 100% of gait cycle (GC), to the successive loading response (≈0–15% of GC), in around 90% of the considered strides. A further superimposition was detected during the push-off phase both between VL and MH activation intervals (38.6 ± 12.8% to 44.1 ± 9.6% of GC) in 21.9 ± 13.6% of strides, and between RF and MH activation intervals (45.9 ± 5.3% to 50.7 ± 9.7 of GC) in 32.7 ± 15.1% of strides. These findings led to identify three different co-contractions among QF and hamstring muscles during able-bodied walking: in early stance (in ≈90% of strides), in push-off (in 25–30% of strides) and in terminal swing (in ≈90% of strides). The co-contraction in terminal swing is the one with the highest levels of muscle excitation intensity. To our knowledge, this analysis represents the first attempt for quantification of QF/hamstring muscles co-contraction in young healthy subjects during normal gait, able to include the physiological variability of the phenomenon.     

Plantar flexor muscle weakness may cause stiff-knee gait

AimThe iterative simulation studies proclaim that plantar flexor (PF) muscle weakness is one of the contributors of stiff knee gait (SKG), although, whether isolated PF weakness generates SKG has not been validated in able-bodied people or individuals with neuromuscular disorders. The aim of the study was to investigate the effects of isolated PF muscle weakness on knee flexion velocity and SKG in healthy individuals.MethodTwenty able-bodied young adults (23 ± 3 years) participated in this study. Passive stretch (PS) protocol was applied until the PF muscle strength dropped 33.1% according to the hand-held dynamometric measurement. Seven additional age-matched able-bodies were compared with participants’ to discriminate the influence of slow-walking. All participants underwent 3D gait analysis before and after the PS. Peak knee flexion angle, range of knee flexion between toe-off and peak knee flexion, total range of knee-flexion, and time of peak knee flexion in swing were selected to describe SKG pattern.ResultsAfter PS, the reduction of plantar flexor muscle strength (33.14%) caused knee flexion velocity drop at toe-off (p = 0.008) and developed SKG pattern by decreasing peak knee flexion (p = 0.0001), range of knee flexion in early swing (p = 0.006), and total knee flexion range (p = 0.002). These parameters were significantly correlated with decreased PF velocity at toe-off (p = 0.015, p = 0.0001, p = 0.005, respectively). The time of peak knee flexion was not significantly different between before and after stretch conditions (p = 0.130).ConclusionsThese findings verified that plantar flexor weakness cause SKG pattern by completing three of SKG parameters. Any treatment protocol that weakens the plantar flexor muscle might impact the SKG pattern.     

Comparison of electromyographic activity of the lower trapezius and serratus anterior muscle in different arm-lifting scapular posterior tilt exercises

ObjectiveTo determine the most effective exercise to specifically activate the scapular posterior tilting muscles by comparing muscle activity generated by different exercises (wall facing arm lift, prone arm lift, backward rocking arm lift, backward rocking diagonal arm lift).DesignRepeated-measure within-subject intervention.ParticipantsThe subjects were 20 healthy young men and women.Main outcome measuresLower trapezius (LT) and serratus anterior (SA) muscle activity was measured when subjects performed the four exercises.ResultsMuscle activity was significantly different among the four exercise positions (p < 0.05). The backward rocking diagonal arm lift elicited significantly greater activity in the LT muscle than did the other exercises (p < 0.05). The backward rocking arm lift showed significantly more activity in the SA muscle than did the other exercises (p < 0.05).ConclusionsClinicians can use these results to develop scapular posterior tilting exercises that specifically activate the target muscle.     

An integrated biomechanical analysis of high speed incline and level treadmill running

PURPOSE: Recent sprint training regimens have used high-speed incline treadmill running to provide enhanced loading of muscles responsible for increasing forward running speed. The goal of this study was to document the joint kinematics, EMG, and swing-phase kinetics of incline treadmill running at 4.5 m x s(-1) with a 30% grade, and compare these data to that of level running under similar conditions. METHODS: Sagittal plane video (200 Hz) and EMG from eight lower extremity muscles were recorded during each of three locomotion conditions: incline running at 4.5 m x s(-1) and 30% grade (INC), level running at 4.5 m x s(-1) (LSS), and level running at the same stride frequency as INC (LSSF). A rigid body model was used to estimate net muscle power and work values at the hip, knee, and ankle during swing. Timing and amplitude of EMG signals for each muscle relative to footstrike were compared between conditions. RESULTS: Stride frequency and percentage of stride spent in stance were significantly higher during INC (1.78 Hz; 32.8%) than in the LSS (1.39 Hz; 28.8%) condition. Stride frequency played an important role, as most measures were more similar between INC and LSSF. Extensor range of motion of all joints during push-off was higher for INC. During INC, average EMG amplitude of the gastrocnemius, soleus, rectus femoris, vastus lateralis, and gluteus maximus were higher during stance, whereas the hamstrings activity amplitudes were lower. Average power and energy generated during hip flexion and extension in the swing phase were greatest during INC. CONCLUSIONS: These data suggest that compared with LSSF and LSS, INC provides enhanced muscular loading of key mono- and bi-articular muscles during both swing and stance phases.     

Biomechanics of slow running and walking with a rocker shoe

Evidence suggests a link between the loading of the Achilles tendon and the magnitude of the ankle internal plantar flexion moment during late stance of gait, which is clinically relevant in the management of Achilles tendinopathy. Some studies showed that rocker shoes can reduce the ankle internal plantar flexion moment. However, the existing evidence is not conclusive and focused on walking and scarce in running. Sixteen healthy runners participated in this study. Lower extremity kinetics, kinematics and electromyographic (EMG) signals of triceps surae and tibialis anterior were quantified for two types of shoes during running and walking. The peak ankle plantar flexion moment was reduced significantly in late stance of running (0.27 Nm/kg; p < 0.001) and walking (0.24 Nm/kg; p < 0.001) with the rocker shoe compared to standard shoe. The ankle power generation and plantar flexion moment impulse were also reduced significantly when running and walking with the rocker shoe (p < 0.001). No significant changes in the knee and hip moments were found in running and walking. A significant delay of the EMG peak, approximately 2% (p < 0.001), was present in the triceps surae when walking with rocker shoes. There were no significant changes in the EMG peak amplitude of triceps surae in running and walking. The peak amplitude of tibialis anterior was significantly increased (64.7 μV, p < 0.001) when walking with rocker shoes. The findings show that rocker shoes reduce the ankle plantar flexion moment during the late stance phase of running and walking in healthy people.     

Neurotomy of the rectus femoris nerve: Short-term effectiveness for spastic stiff knee gait: Clinical assessment and quantitative gait analysis

BackgroundStiff knee gait is a troublesome gait disturbance related to spastic paresis, frequently associated with overactivity of the rectus femoris muscle in the swing phase of gait.ObjectiveThe aim of this study was to assess the short-term effects of rectus femoris neurotomy for the treatment of spastic stiff-knee gait in patients with hemiparesis.Patients and methodsAn Intervention study (before-after trial) with an observational design was carried out in a university hospital. Seven ambulatory patients with hemiparesis of spinal or cerebral origin and spastic stiff-knee gait, which had previously been improved by botulinum toxin injections, were proposed a selective neurotomy of the rectus femoris muscle. A functional evaluation (Functional Ambulation Classification and maximal walking distance), clinical evaluation (spasticity – Ashworth scale and Duncan-Ely test, muscle strength – Medical Research Council scale), and quantitative gait analysis (spatiotemporal parameters, stiff knee gait-related kinematic and kinetic parameters, and dynamic electromyography of rectus femoris) were performed as outcome measures, before and 3 months after rectus femoris neurotomy.ResultsCompared with preoperative values, there was a significant increase in maximal walking distance, gait speed, and stride length at 3 months. All kinematic parameters improved, and the average early swing phase knee extension moment decreased. The duration of the rectus femoris burst decreased post-op.ConclusionThis study is the first to show that rectus femoris neurotomy helps to normalise muscle activity during gait, and results in improvements in kinetic, kinematic, and functional parameters in patients with spastic stiff knee gait.     

Contoured in-shoe foot orthoses increase mid-foot plantar contact area when compared with a flat insert during cycling

ObjectivesTo determine the effect of contouring of an in-shoe foot orthosis on plantar contact area and surface pressure, as well as perceived comfort and support at the foot-orthosis interface during stationary cycling.DesignA randomised, repeated measures control study.MethodsTwelve cyclists performed steady-state seated cycling at a cadence of 90 rpm using a contoured orthosis and a flat insert of similar hardness. Contact area (CA) and plantar mean pressure (PP) were measured using the PEDAR^® system, determined for seven discrete plantar regions and represented as the percentage of the total CA and PP respectively (CA% and PP%). Perceived comfort and support were rated using a visual analogue scale (VAS).ResultsThe contoured orthosis produced a significantly greater CA% at the medial midfoot (p = 0.001) and lateral midfoot (p = 0.009) with a standardised mean difference (SMD) of 1.3 and 0.9 respectively. The contoured orthosis also produced a significantly greater PP% at the hallux (p = 0.003) compared to the flat insert with a SMD of 1.1. There was a small non-significant effect (SMD < 0.4) for the perceived comfort measures between conditions, but perceived support was significantly greater at the arch (p = 0.000) and heel (p = 0.013) with the contoured orthoses (SMD of 1.5 and 0.9, respectively).ConclusionsContoured orthoses influenced the plantar surface of the foot by increasing contact area as well as a perception of greater support at the midfoot while increasing relative pressure through the hallux when compared to a flat insert during stationary cycling. No difference in perceived comfort was noted.     

Muscle activation patterns of the lumbo-pelvic-hip complex during walking gait before and after exercise

The lumbo-pelvic-hip core complex consists of musculoskeletal structures that stabilize the spine and pelvis, however fatigue may affect muscle recruitment, active muscle stiffness and trunk kinematics, compromising trunk stability. The purpose of this study was to compare trunk muscle activation patterns, and trunk and lower extremity kinematics during walking gait before and after exercise. Surface electrodes were placed over the rectus abdominis, external oblique, erector spinae, gluteus medius, vastus lateralis, and vastus medialis of twenty-five healthy inidviduals. Means and 95% confidence intervals for muscle amplitude, muscle onsent and kinematics for 0–100% of the gait cycle were compared before and after exercise. Mean differences (MD) and standard deviations were calculated for all significant differences. The amplitude increased in the rectus abdominis during loading (MD = 0.67 ± 0.11), midstance (MD = 0.75 ± 0.04), terminal stance (MD = 0.58 ± 0.04), and late swing (MD = 0.75 ± 0.07) after exercise. Amplitude also increased during swing phase in the erector spinae (MD = 0.92 ± 0.11), vastus lateralis (MD = 1.12 ± 0.30), and vastus medialis (MD = 1.80 ± 0.19) after exercise. There was less trunk and hip rotation from initial contact to midstance after exercise. Neuromuscular fatigue significantly influenced the activation patterns of superficial musculature and kinematics of the lumbo-pelvic-hip complex during walking. Increased muscle activation with decreased movement in a fatigued state may represent an effort to increase trunk stiffness to protect lumbo-pelvic-hip structures from overload.     

Dose–response effects of customised foot orthoses on lower limb muscle activity and plantar pressures in pronated foot type

Customised foot orthoses (FOs) featuring extrinsic rearfoot posting are commonly prescribed for individuals with a symptomatic pronated foot type. By altering the angle of the posting it is purported that a controlled dose–response effect during the stance phase of gait can be achieved, however these biomechanical changes have yet to be characterised. Customised FOs were administered to participant groups with symptomatic pronated foot types and asymptomatic normal foot types. The electromyographic (EMG) and plantar pressure effects of varying the dose were measured. Dose was varied by changing the angle of posting from 6° lateral to 10° medial in 2° steps on customised devices produced using computer aided orthoses design software. No effects due to posting level were found for EMG variables. Significant group effects were seen with customised FOs reducing above knee muscle activity in pronated foot types compared to normal foot types (biceps femoris p = 0.022; vastus lateralis p < 0.001; vastus medialis p = 0.001). Interaction effects were seen for gastrocnemius medialis and soleus. Significant linear effects of posting level were seen for plantar pressure at the lateral rearfoot (p = 0.001), midfoot (p < 0.001) and lateral forefoot (p = 0.002). A group effect was also seen for plantar pressure at the medial heel (p = 0.009). This study provides evidence that a customised FOs can provide a dose response effect for selected plantar pressure variables, but no such effect could be identified for muscle activity. Foot type may play an important role in the effect of customised orthoses on activity of muscles above the knee.     

Effect of aging on regional neuromuscular regulation within human rectus femoris muscle during stair ascent and descent

Our recent studies showed the rectus femoris (RF) muscle is regionally regulated during the level walking and this unique neuromuscular activation pattern is influenced by aging (Watanabe et al., 2014, 2016 J Biomech). We aimed to investigate and compare regional neuromuscular activation patterns along the RF muscle between the young and elderly during the stair walking. Fourteen young men (age: 20.4 ± 1.0 years) and 14 elderly men (age: 73.8 ± 5.9 years) performed the stair ascent and descent. Fifteen trials of three steps were performed for both stair ascent and descent. The spatial distribution of surface electromyography (EMG) within the RF muscle was assessed by central locus activation (CLA), which is calculated from 18 surface electrodes along the longitudinal line of the muscle. CLA was significantly moved along the muscle during the stair ascent and descent in both young and elderly (p < 0.05). Significant differences in CLA were showed at the stance phase of the ascent (12.5 ± 0.7 and 11.4 ± 1.7 cm from most proximal electrodes for the young and elderly, p < 0.05) and at the swing phase of the descent (11.4 ± 1.5 and 10.3 ± 1.5 cm from most proximal electrodes for the young and elderly, p < 0.05). These results suggest that the regional neuromuscular activation within the RF muscle is affected by aging during the stair walking.     

Rectus femoris transfer in cerebral palsy patients with stiff knee gait

BackgroundAlthough several studies have reported on the outcomes of rectus femoris transfer (RFT), few have investigated the multiple factors that could affect the results. Therefore, we evaluated the outcomes of RFT and analyzed factors that influence improvement and annual change in knee motion after surgery in patients with cerebral palsy (CP).MethodsWe reviewed ambulatory patients with CP who were followed up after they had undergone RFT as part of a single-event multilevel surgery (SEMLS) and who had undergone preoperative and postoperative three-dimensional (3D) gait analysis between January 1995 and December 2012. Relevant kinematic values, including peak knee flexion, knee range of motion, and timing of peak knee flexion in the swing phase and gait deviation index (GDI) score, were the outcome measures. Improvements in rate of angle and GDI score were adjusted by multiple factors such as sex, Gross Motor Function Classification System (GMFCS) level, anatomic type of CP, and concomitant surgeries as the fixed effects, and follow-up duration, laterality, and each subject as the random effects, all of which was performed using a linear mixed model.ResultsA total of 290 patients (487 limbs) and 612 3D gait analysis (2–4 per patient) results were finally included in this study. At 2 years after RFT, estimated mean peak knee flexion (1.2°, p = 0.005), estimated mean knee range of motion (10.7°, p < 0.001), and estimated mean GDI score (7.3, p < 0.001) increased significantly. Peak knee flexion in the swing phase occurred 5.4% earlier after surgery compared with that at baseline (p < 0.001). In serial postoperative gait analyses, peak knee flexion in the swing phase occurred 0.8% earlier per year in patients with GMFCS level I or II (p = 0.021).ConclusionsRFT as part of a SEMLS was effective in treating stiff knee gait. In serial postoperative gait analyses, patients with GMFCS level I or II showed better prognosis than those with level III with regard to timing of peak knee flexion in the swing phase.Level of evidencePrognostic level IV.     

Lower extremity kinematic asymmetry in male and female athletes performing jump-landing tasks

ObjectivesHigher side-to-side asymmetry among female athletes compared to their male counterparts during bilateral athletic tasks such as landing from a jump has been proposed as a potential source of non contact knee injuries. However, the kinematic symmetry and potential sex differences during the initial (and most dangerous) phase of bilateral landings have not been examined. The objective of this project is to evaluate lower extremity kinematic asymmetry among recreational athletes during forward jump landing and drop landing tasks.DesignRepeated measures laboratory experiment.MethodsThirteen male and 15 female athletes performed landing tasks on a force plate while kinematic data were collected. Kinematic asymmetry between legs was calculated for the initial phase of landing for lower extremity kinematics. ANOVA tests and effect size calculations were used to measure the effect of sex, landing task and their interaction on kinematic asymmetry.ResultsAthletes exhibited higher asymmetry for knee valgus (d = 0.5, p = 0.006) and hip adduction (d = 0.5, p = 0.057) when performing forward compared to drop landings. Females landed with greater knee valgus asymmetry than males during forward landings (d = 0.7, p = 0.078) and with greater ankle abduction asymmetry during drop landings (d = 0.5, 0.091).ConclusionsFemale athletes exhibited greater frontal plane knee and ankle kinematic asymmetry than males during forward landings which may be related to the higher rate of ACL injury. Forward landings elicited greater hip adduction and knee valgus asymmetries than drop landings and, therefore it may be more appropriate for field testing when screening for asymmetries.     

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

ObjectivesTo 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.DesignExperimental, randomized trial.MethodsTwenty-two resistance-trained ice hockey players (18 ± 1 year) 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.ResultsSimilar 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).ConclusionsBoth 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.