The Effects of a 12-Week-Long Sand Exercise Training Program on Neuromechanical and Functional Parameters in Type II Diabetic Patients with Neuropathy

Studies have proven the effectiveness of different weight-bearing exercise interventions for diabetic patients with neuropathy; however, several adverse effects were reported using solid surfaces. Thus, in the present study, we investigated the effects of a novel sand exercise training intervention on biomechanical and functional parameters in seven diabetic patients (age = 62.7 ± 9.7 years) with neuropathy. Patients underwent a 12-week sand exercise training program, using strengthening, stretching, balance, and gait exercises. They were tested for ankle plantar- and dorsiflexion peak torque, active range of motion (ROM), timed up and go (TUG), and bilateral static balance. EMG activity of tibialis anterior (TA), gastrocnemius medialis (GM), and lateralis (GL) muscles were measured during unilateral isometric contraction in plantar- and dorsiflexion. In the intervention period, plantarflexion peak torque improved significantly (p = 0.033), while dorsiflexion torque remained unchanged. Plantar- and dorsiflexion ROM increased (p = 0.032) and (p = 0.021), respectively. EMG activity of GM (p = 0.005) and GL (p = 0.002) measured during dorsiflexion and postural sway in the balance test, as well as time to complete the TUG test, decreased significantly (p = 0.021) and (p = 0.002), respectively. No adverse effect was reported during the intervention period. We concluded that sand exercise training can be a safe and effective method to improve plantarflexion strength, ankle flexibility, and balance, which is reflected in better gait function in patients with diabetic peripheral neuropathy (DPN).

Kinematics and muscle activity of the lower limb during single-leg stance on the two sides of the Togu Jumper

Purpose: Togu Jumper is a both sides utilized balance training device, which consists of an inflated rubber hemisphere attached to a rigid platform. It has been shown to be effective in improving postural control but there are no recommendations for the usage of the sides. Our aim was to examine leg muscle activity and kinematics in response to a single-leg stance on the two sides of the Togu Jumper and the floor. Methods: In 14 female subjects, linear acceleration of leg segments, segmental angular sway, and myoelectric activity of 8 leg muscles were recorded in the three stance conditions. Results: Except gluteus medius and gastrocnemius medialis, all muscles were more active when balancing on either Togu Jumper side compared to the floor (p < 0.001), but there was no difference between the two sides in any muscles. Linear acceleration was the greatest in the frontal plane on the flat Togu side in the case of the foot (p < 0.001). Pelvis acceleration was unaffected by the balance conditions. Segmental angular sway was the greatest in the frontal plane, on the bladder side in the foot segment (p < 0.001). No difference was found among the three conditions (all p > 0.05) in the case of the shank, thigh, and pelvis. Conclusion: The use of the two Togu Jumper sides produced different balance strategies in the foot segment and induced no difference in equilibrium procedures at the level of the pelvis.

Frontal Plane Neurokinematic Mechanisms Stabilizing the Knee and the Pelvis during Unilateral Countermovement Jump in Young Trained Males

(1) The unilateral countermovement jump is commonly used to examine frontal plane kinetics during unilateral loading and to identify athletes with an increased risk of lower limb injuries. In the present study, we examined the biomechanical mechanisms of knee and pelvis stabilization during unilateral vertical jumps. (2) Healthy males performed jumps on a force plate with the dominant leg. Activity of the dominant-side gluteus medius and the contralateral-side quadratus lumborum and erector spinae muscles was recorded with surface EMG. The EMG data were normalized to the EMG activity recorded during maximal voluntary isometric hip abduction and lateral trunk flexion contractions. During jumps, the propulsive impulse was measured, and the pelvis and thigh segmental orientation angles in the frontal plane were recorded and synchronized with the EMG data. (3) The magnitude of knee valgus during the jump did not correlate with hip abduction force, but negatively correlated with gluteus medius activity. This correlation became stronger when gluteus medius activity was normalized to hip abduction force. Propulsive impulse did not correlate with any neuromechanical measurement. (4) We conclude that hip abduction force itself does not regulate the magnitude of knee valgus during unilateral jumps; rather, the gluteus medius should be highly activated to increase frontal-plane knee joint stability.

Biosignal processing methods to explore the effects of side-dominance on patterns of bi- and unilateral standing stability in healthy young adults

We examined the effects of side-dominance on the laterality of standing stability using ground reaction force, motion capture (MoCap), and EMG data in healthy young adults. We recruited participants with strong right (n = 15) and left (n = 9) hand and leg dominance (side-dominance). They stood on one or two legs on a pair of synchronized force platforms for 50 s with 60 s rest between three randomized stance trials. In addition to 23 CoP-related variables, we also computed six MoCap variables representing each lower-limb joint motion time series. Moreover, 39 time- and frequency-domain features of EMG data from five muscles in three muscle groups were analyzed. Data from the multitude of biosignals converged and revealed concordant patterns: no differences occurred between left- and right-side dominant participants in kinetic, kinematic, or EMG outcomes during bipedal stance. Regarding single leg stance, larger knee but lower ankle joint kinematic values appeared in left vs right-sided participants during non-dominant stance. Left-vs right-sided participants also had lower medial gastrocnemius EMG activation during non-dominant stance. While right-side dominant participants always produced larger values for kinematic data of ankle joint and medial gastrocnemius EMG activation during non-dominant vs dominant unilateral stance, this pattern was the opposite for left-sided participants, showing larger values when standing on their dominant vs non-dominant leg, i.e., participants had a more stable balance when standing on their right leg. Our results suggest that side-dominance affects biomechanical and neuromuscular control strategies during unilateral standing.

The impact of aerobic and resistance training intensity on markers of neuroplasticity in health and disease

OBJECTIVE

To determine the effects of low- vs. high-intensity aerobic and resistance training on motor and cognitive function, brain activation, brain structure, and neurochemical markers of neuroplasticity and the association thereof in healthy young and older adults and in patients with multiple sclerosis, Parkinson's disease, and stroke.

DESIGN

Systematic review and robust variance estimation meta-analysis with meta-regression.

DATA SOURCES

Systematic search of MEDLINE, Web of Science, and CINAHL databases.

RESULTS

Fifty studies with 60 intervention arms and 2283 in-analyses participants were included. Due to the low number of studies, the three patient groups were combined and analyzed as a single group. Overall, low- (g=0.19, p = 0.024) and high-intensity exercise (g=0.40, p = 0.001) improved neuroplasticity. Exercise intensity scaled with neuroplasticity only in healthy young adults but not in healthy older adults or patient groups. Exercise-induced improvements in neuroplasticity were associated with changes in motor but not cognitive outcomes.

CONCLUSION

Exercise intensity is an important variable to dose and individualize the exercise stimulus for healthy young individuals but not necessarily for healthy older adults and neurological patients. This conclusion warrants caution because studies are needed that directly compare the effects of low- vs. high-intensity exercise on neuroplasticity to determine if such changes are mechanistically and incrementally linked to improved cognition and motor function.

No Difference in the Acute Effects of Randomization vs. Blocking of Units of Lower-Extremity Proprioceptive Training on Balance and Postural Control in Young Healthy Male Adults

Random practice is a form of differential learning and its favorable acute effects on motor performance are well described when visual tasks are practiced. However, no study to date has investigated the acute effects of differential learning using variable proprioceptive stimuli instead of the visual cues. The aim of the present study was to compare the acute effects of randomized versus blocked lower-extremity proprioceptive training stimuli on balance and postural adjustments. In two conditions, healthy young males (n = 15, age = 23 years) performed 16 one-legged landings on a board tilted in four directions: 1) tilt direction unknown and randomized and 2) tilt direction known with order of presentation blocked. Multi-segmental angular sway while balancing on an unstable surface and postural responses to perturbation stimulus by surface tilts were measured before and 4 min after training. Overall frontal-plane postural sway on the unstable surface decreased (p < 0.05, η² = 0.022) in both conditions, while sagittal-plane postural sway remained unchanged. When the surface was toes-up tilted in the perturbation test, the sagittal-plane shank-thigh-pelvis alignment improved in both conditions (p < 0.05, η² = 0.017), but the direction of the segmental positioning was non-uniform across participants. We conclude that randomization vs. blocking of units of lower-extremity proprioceptive training did not affect balance and postural control in our cohort of healthy young adults but the improvements were test-specific.

The effects of eccentric hamstring exercise training in young female handball players

Purpose

The multidimensional role of hamstring muscle group strength in athletic performance and injury prevention is well documented, and nordic hamstring exercise (NHE) is a popular method for the development of hamstring strength. Our aim was to examine the EMG characteristics of the eccentric NHE as well as the effects of long-term eccentric NHE training on muscle strength and vertical jump performance in 10- to 11-year-old female handball players.

Methods

Players from the same handball team were randomly assigned to an eccentric NHE training (13 players) or a control group (10 players). Both groups continued their regular handball training routine, but the NHE group performed additional eccentric NHE exercises once or twice a week, with progressively increasing volume, over 20 weeks. To test training effects, countermovement jump (CMJ) height, eccentric hamstring impulse, peak torque, and angle of peak torque were evaluated before, during and after the training period. In the pre-exercise test, EMG activity of the medial and lateral hamstring muscle was also assessed during NHE.

Results

Hamstring activities ranged between 98 and 129%. Lateral hamstring activity was greater than medial only in the right leg during NHE. Eccentric hamstring impulse improved in both legs at 10 weeks in both groups. Then, at 20 weeks, it remained unchanged in the NHE but decreased in controls. A similar adaptation was seen in eccentric hamstring torque, without change in the optimum knee angle. CMJ height improved only in the NHE.

Conclusion

It is concluded that NHE activates the hamstring musculature effectively, and a favourable mechanical adaptation to long-term NHE exercise in girls can be triggered as early as 11 years of age.

Clinical Effect of End-range Maitland Mobilization in the Management of Knee Osteoarthritis - A Pilot Study

BACKGROUND/AIM

Different manual therapy techniques and conservative therapy have been used separately for alleviation of pain and improvement of physical function in patients with knee osteoarthritis (KOA). However, no study has reported the effect of combination of these treatment modalities in the management of KOA. Our aim was to test the feasibility of the study design and to compare the effect of end-range Maitland mobilization to conservative therapy in KOA.

PATIENTS AND METHODS

Fifteen patients (conservative therapy group: CG) received conservative therapy alone, fifteen patients (Maitland plus conservative therapy group: M+CG) received additionally end-range Maitland mobilization during the 3-week study period. Outcomes were pain intensity, measured with visual analogue scale (VAS) in general and during functional activities, passive range of motion (PROM) and peak muscle force during knee flexion and extension, Timed Up and Go test and 6-Minute Walk Test (6MWT).

RESULTS

All outcomes improved significantly in both groups. Magnitude of changes was significantly greater in M+CG compared to CG regarding all VAS pain scores, flexion PROM of both knees, right hamstring peak muscle force and 6MWT.

CONCLUSION

With few modifications, this study design seems feasible for the comparison of end-range Maitland mobilization with conservative therapy in KOA. Moreover, end-range Maitland mobilization in addition to conservative therapy appeared more effective in relief of pain and improvement of functional status than conservative therapy alone in KOA.

Muscle damage in response to a single bout of high intensity concentric exercise in patients with Pompe disease

Background

In Pompe disease, resistance exercise could be an effective treatment to delay motor function impairment, however, the acute effects of this exercise modality are unclear.

Methods

In a prospective cohort study, we compared responses to a single bout of resistance exercise by serum markers of muscle damage and quantitative muscle magnetic resonance imaging (MRI) in patients (n=12) and age- and gender-matched healthy controls (n=12). Participants performed 50 maximal effort concentric knee flexions on a dynamometer.

Results

Twenty-four hours after exercise, levels of serum creatine kinase, lactate dehydrogenase and myoglobin increased in controls. In contrast, only myoglobin level increased in patients. All elevated serum markers declined by 48 hours after exercise in both groups. Mild soreness developed at 24 hours, which disappeared at 48 hours in both groups. In controls, MRI R2* relaxation rate reduced immediately and 24 hours after exercise, indicating increased water content and muscle perfusion. In patients, exercise had no effect on R2* values. The resistance exercise did not induce acute strength deficit in patients, rather, patients increased their strength by 24 hours. When serum marker changes were normalized to the magnitude of knee flexor tension developed during exercise, lactate dehydrogenase response was greater in patients.

Conclusions

Late-onset Pompe disease did not exacerbate exercise-induced muscle damage, however, lactate dehydrogenase may be monitored to screen high responders during high intensity resistance exercise interventions.

Effects of short-term in-season plyometric training in adolescent female basketball players

In this study, we tested the hypothesis that, during the regular in-seasonal basketball training, an additional 7-week plyometric training program improves lower extremity strength, balance, agility, and jump performance in adolescent female basketball players. Eighteen female basketball players less than 17 years of age were randomly assigned into an experimental group (plyometric training) and a control group. Both groups underwent the same basketball training program. Pre- and post-training test periods included quadriceps and hamstring strength, balance, jump performance, and agility measurements. Illinois agility test time (p = 0.000) and quadriceps strength (p = 0.035) increased uniformly in the two groups. Significant group by test period interaction was found for countermovement jump (p = 0.007), and countermovement height reduced significantly in the plyometric training group (p = 0.012), while it remained unchanged in controls. No significant change was found for T agility test, balance, hamstring strength or H:Q ratio. This study shows that the training program used in-season did not improve the measured variables, except for knee extensor strength. It is possible that regular basketball trainings and games combined with high-volume plyometric training did not show positive functional effects because of the fatigue caused by incomplete recovery between sessions.

Effects of side-dominance on knee joint proprioceptive target-matching asymmetries

AIMS

Right- and left-side-dominant individuals reveal target-matching asymmetries between joints of the dominant and non-dominant upper limbs. However, it is unclear if such asymmetries are also present in lower limb's joints. We hypothesized that right-side-dominant participants perform knee joint target-matching tasks more accurately with their non-dominant leg compared to left-side-dominant participants.

METHODS

Participants performed position sense tasks using each leg by moving each limb separately and passively on an isokinetic dynamometer.

RESULTS

Side-dominance affected (p < 0.05) knee joint absolute position errors only in the non-dominant leg but not in the dominant leg: right-side-dominant participants produced less absolute position errors (2.82° ± 0.72°) with the non-dominant leg compared to left-side-dominant young participants (3.54° ± 0.33°).

CONCLUSIONS

In conclusion, right-side-dominant participants tend to perform a target-matching task more accurately with the non-dominant leg compared to left-side-dominant participants. Our results extend the literature by showing that right-hemisphere specialization under proprioceptive target-matching tasks may be not evident at the lower limb joints.

Acute neuromechanical modifications and 24-h recovery in quadriceps muscle after maximal stretch-shortening cycle exercise

In the present study we investigated the acute and the delayed changes in corticospinal excitability and in the neuromechanical properties of the quadriceps muscle after maximal intensity stretch-shortening cycle exercise. Ten young males performed 150 jumps to provoke fatigue and muscle damage. Voluntary force, various electrically evoked force variables, and corticospinal excitability were measured at baseline, immediately (IP) and at 24 h post-exercise. Voluntary force, single twitch force, and low frequency force decreased at IP (p < 0.05) but recovered at 24 h, although mild soreness developed in the quadriceps. High frequency force, voluntary activation, and corticospinal excitability remained unchanged. However, vastus lateralis myoelectric activity increased from baseline to IP (p < 0.05). The jumps selectively induced low frequency peripheral fatigue, and central mechanisms did not mediate the acute loss of voluntary force. Because soreness developed at 24 h post-exercise, all force variables recovered, and vastus lateralis electric activity increased, we argue that a dual process of muscle damage, and early neural adaptation as a compensation mechanism took place after the maximal stretch-shortening cycle exercise.

Plasma Actin, Gelsolin and Orosomucoid Levels after Eccentric Exercise

The present study investigated the acute effect of eccentric exercise on blood plasma actin, gelsolin (GSN) and orosomucoid (AGP) levels in untrained and moderately trained individuals, and their correlation with exercise induced muscle damage (EIMD) markers (CK, intensity of muscle soreness and maximal voluntary contraction torque deficit). Healthy physical education students (6 untrained, 12 moderately trained) participated in this research. Actin, GSN, AGP and CK levels were measured in blood plasma at baseline, immediately, 1 h, 6 h and 24 h post-exercise comprising 90 eccentric quadriceps contractions performed on a dynamometer. There was significant time main effect for GSN, AGP, CK and significant difference was found between baseline and the lowest value of post-exercise GSN (p < 0.05), as well as baseline and the highest value of post-exercise AGP (p < 0.05). Relationships were found between GSN levels and other indirect EIMD markers (between all GSN levels at post-exercise and CK activity at 6 h, p < 0.05; GSNMIN and muscle soreness at post-exercise, p < 0.04), GSN and AGP; however, actin did not correlate at any time points with GSN. Actin, GSN, AGP and CK responses after eccentric exercise do not seem sensitive to training status. The plasma actin level is used as an indicator of injury, however, our results suggest that it is not an accurate marker of EIMD, while plasma GSN concentrations show a better relationship with EIMD and the post-exercise inflammatory process. The elevated plasma AGP and the correlation between GSN and AGP seem to be promising for assessment of exercise-induced muscle injury.

Mechanical, hormonal, and hypertrophic adaptations to 10 weeks of eccentric and stretch-shortening cycle exercise training in old males

The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60-70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%]) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12-15% lower (p<0.05). Both programs increased quadriceps size 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly.

Changes in metabolic and muscle damage indicators following a single bout of jump training on stair versus at level

We hypothesized that stair-jump exercise would induce less muscle damage and greater acute metabolic responses than level-jumps.

METHODS

Trained males executed 100 unilateral jumps on stairs with one leg, and at level with the other leg, with two weeks hiatus. Maximal isometric voluntary torque (MVC) and rate of torque development (RTD)in the quadriceps, and unilateral vertical jump height (VJ) were determined in the trained leg at pre-exercise,immediately at post- (IP), 24 h and 48 h after exercise. Serum creatine kinase (CK) level and delayed onset muscle soreness (DOMS) were evaluated at pre-exercise, 24 h and 48 h. Acute lactate and heart rate responses were also measured.

RESULTS

Lactate and heart rate at IP increased similarly under the two conditions. CK was elevated and MVC was depressed while RTD and VJ remained unchanged at 24 h in both types of training. MVC recovered at 48 h only after stair-jump exercise. DOMS developed only after level-jumps. Except DOMS, no effects of condition were found in any other variables.

CONCLUSIONS

We conclude that vigorous stair-jump exercise highly stresses the aerobic and the anaerobic energy system, and it preserves power and rapid torque generating ability 24 h after exercise. Stair-jump could be one alternative exercise to prevent muscle soreness.

Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage

To determine the acute task and stretch-load dependency of neuromuscular impairments after muscle-damaging exercises, we examined the magnitude of strength deficits in isometric and stretch-shortening cycle (SSC) contractions after a single bout of exercise. Ten trained men performed 90 unilateral isokinetic eccentric-concentric knee extensions on a dynamometer. Plasma creatine kinase activity, muscle soreness, maximal isometric torque, short-range stiffness, and peak torque in the eccentric phase of the SSC contraction at 3 stretch-loads (120, 150, and 180 J) were determined in the quadriceps before and 24 hours after exercise. During SSC, positive mechanical work and efficiency were also calculated. Creatine kinase and soreness increased at 24 hours (p < 0.05). In each of the 3 stretch-load conditions, muscle damage affected short-range stiffness less than isometric and peak SSC torque (p < 0.05), providing evidence for a selective impairment in contractile function after muscle damage. With greater SSC stretch-load peak, SSC torque deficit increased linearly, whereas short-range stiffness deficit was unaffected. Efficiency declined only at the 180-J condition (p < 0.05) as a result of decreased positive work (p < 0.05). It was concluded that intense exercise produced microtrauma in the muscle, and a selective loss of force generating capacity, which suggests greater damage to the contractile machinery. Practitioners may expect greater acute impairment of force generation in movements that use large loads in their daily training drills. However, altered knee flexion strategy during SSC may compensate for the force deficit, preserving mechanical efficiency at smaller stretch-loads.

Mechanical, biochemical, and electromyographic responses to short-term eccentric-concentric knee extensor training in humans

This study examined the effects of short-term eccentric-concentric knee extensor training on mechanical and biochemical variables, myoelectric activity, and muscle soreness. Seventeen men were assigned to either experimental (E, n = 10) or control group (C, n = 7). Group E performed 90 maximal isokinetic eccentric-concentric knee extensor contractions on each of 3 consecutive days (Tr1-Tr3) followed by 1-day rest, and then on 4 more consecutive days (Tr4-Tr7). Peak eccentric torque of each contraction during the training was recorded and averaged for each session (MTr). Maximal isometric torque (M0), eccentric torque (M(ecc)), integrated electromyography (iEMG), plasma creatine kinase (CK), and lactate dehydrogenase (LDH) activities were measured before, immediately, 24, 48, and 72 hours after Tr1, at 1 and 3 days after Tr7. Group C did not train but performed all exercise tests; CK and LDH were measured at 3 time points only. Acutely, M0 and M(ecc) decreased and CK, LDH, and soreness increased more in E than in C 24 hours after Tr1. Chronically, MTr and M0 increased more in E than C by Tr7 and CK, LDH, and muscle soreness gradually decreased by Tr7 whereas iEMG increased more in E than in C after Tr3 through Tr7. High-intensity short-term eccentric-concentric knee extensor exercise training produced immediate reductions in maximal voluntary force. Most likely neural adaptations contributed to rapid recovery and strength adaptations because maximal voluntary force increased by the end of the training protocol in previously trained healthy adults.