ORCID Profile
0000-0002-5331-9424
Current Organisation
University of Jyväskylä
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Publisher: MDPI AG
Date: 15-08-2023
Abstract: Sensorimotor training and strength training can improve balance control. Currently, little is known about how repeated balance perturbation training affects balance performance and its neural mechanisms. This study investigated corticospinal adaptation assessed by transcranial magnetic stimulation (TMS) and Hoffman-reflex (H-reflex) measurements during balance perturbation induced by perturbation training. Fourteen subjects completed three perturbation sessions (PS1, PS2, and PS3). The perturbation system operated at 0.25 m/s, accelerating at 2.5 m/s2 over a 0.3 m displacement in anterior and posterior directions. Subjects were trained by over 200 perturbations in PS2. In PS1 and PS3, TMS and electrical stimulation elicited motor evoked potentials (MEP) and H-reflexes in the right leg soleus muscle, at standing rest and two time points (40 ms and 140 ms) after perturbation. Body sway was assessed using the displacement and velocity of the center of pressure (COP), which showed a decrease in PS3. No significant changes were observed in MEP or H-reflex between sessions. Nevertheless, Δ MEP at 40 ms demonstrated a positive correlation with Δ COP, while Δ H-reflex at 40 ms demonstrated a negative correlation with Δ COP. Balance perturbation training led to less body sway and a potential increase in spinal-level involvement, indicating that movement automaticity may be suggested after perturbation training.
Publisher: Springer Science and Business Media LLC
Date: 21-06-2022
DOI: 10.1007/S00421-022-04981-9
Abstract: Long-term sports training, such as skill and endurance training, leads to specific neuroplasticity. However, it remains unclear if muscle stretch-induced proprioceptive feedback influences corticospinal facilitation/inhibition differently between skill- and endurance-trained athletes. This study investigated modulation of corticospinal excitability following rapid ankle dorsiflexion between well-trained skill and endurance athletes. Ten skill- and ten endurance-trained athletes participated in the study. Corticospinal excitability was tested by single- and paired-pulse transcranial magnetic stimulations (TMS) at three different latencies following passive rapid ankle dorsiflexion. Motor evoked potential (MEP), short-latency intracortical inhibition (SICI), intracortical facilitation (ICF), and long-latency intracortical inhibition (LICI) were recorded by surface electromyography from the soleus muscle. Compared to immediately before ankle dorsiflexion (Onset), TMS induced significantly greater MEPs during the supraspinal reaction period (~ 120 ms after short-latency reflex, SLR) in the skill group only (from 1.7 ± 1.0 to 2.7 ± 1.8%M-max, P = 0.005) despite both conditions being passive. ICF was significantly greater over all latencies in skill than endurance athletes ( F (3, 45) = 4.64, P = 0.007), although no between-group differences for stimulations at specific latencies (e.g., at SLR) were observed. The skill group showed higher corticospinal excitability during the supraspinal reaction phase, which may indicate a “priming” of corticospinal excitability following rapid ankle dorsiflexion for a supraspinal reaction post-stretch, which appears absent in endurance-trained athletes.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.JELEKIN.2014.01.010
Abstract: The present study compared neuromuscular adaptations to 12weeks of plyometric (PLY) or pneumatic (PNE) power training and their effects on dynamic balance control. Twenty-two older adults aged 60-70 (PLY n=9, PNE n=11) participated in the study. Measurements were conducted at Pre, 4, 8 and 12weeks. Dynamic balance was assessed as anterior-posterior center of pressure (COP) displacement in response to sudden perturbations. Explosive isometric knee extension and plantar flexion maximal voluntary contractions (MVCs) were performed. Maximal drop jump performance from optimal dropping height was measured in a sledge ergometer. Increases in knee extensor and ankle plantar flexor torque and muscle activity were higher and occurred sooner in PNE, whereas in drop jumping, PLY showed a clearer increase in optimal drop height (24%, p<0.01) after 8weeks of training and soleus muscle activity after 12weeks of training. In spite of these training mode specific adaptations, both groups showed similar improvements in dynamic balance control after 4weeks of training (PLY 38%, p<0.001 PNE 31%, p<0.001) and no change thereafter. These results show that although power and plyometric training may involve different neural adaptation mechanisms, both training modes can produce similar improvements in dynamic balance control in older in iduals. As COP displacement was negatively correlated with rapid knee extension torque in both groups (PLY r=-0.775, p<0.05 PNE r=-0.734, p<0.05) after training, the results also highlight the importance of targeting rapid force production when training older adults to improve dynamic balance.
Publisher: American Physiological Society
Date: 12-2013
Abstract: This study investigated age-related differences in dynamic balance control and its connection to reflexes and explosive isometric plantar flexor torque in 19 males (9 Young aged 20–33 yr, 10 Elderly aged 61–72 yr). Dynamic balance was measured during Slow (15 cm/s) and Fast (25 cm/s) anterior and posterior perturbations. H/M-ratio was measured at 20% of maximal M-wave (H/M 20% ) 10, 30, and 90 ms after perturbations. Stretch reflexes were measured from tibialis anterior and soleus during anterior and posterior perturbations, respectively. In Slow, Elderly exhibited larger peak center-of-pressure (COP) displacement (15% P 0.05) during anterior perturbations. In Fast, Young showed a trend for faster recovery (37% P = 0.086) after anterior perturbations. M-wave latency was similar between groups (6.2 ± 0.7 vs. 6.9 ± 1.2 ms), whereas Elderly showed a longer H-reflex latency (33.7 ± 2.3 vs. 36.4 ± 1.7 ms P 0.01). H/M 20% was higher in Young 30 ms after Fast anterior (50% P 0.05) and posterior (51% P 0.05) perturbations. Plantar flexor rapid torque was also higher in Young (26% P 0.05). After combining both groups' data, H/M 20% correlated negatively with Slow peak COP displacement ( r = −0.510, P 0.05) and positively with Fast recovery time ( r = 0.580, P 0.05) for anterior perturbations. Age-related differences in balance control seem to be more evident in anterior than posterior perturbations, and rapid sensory feedback is generally important for balance perturbation recovery.
No related grants have been discovered for Jarmo Piirainen.