during badminton games , it is necessary for players to use high - level stroke skills in 
 various situations1 .
players need to be 
 able to select and execute a large number of stroke , in different situations , after 
 selecting highly strategic shots to disrupt their opponent s readiness , rather than simply 
 returning the shuttlecock2 .
for example , 
 when an opponent takes up the ready position in front of the net , it is appropriate to 
 return the shuttlecock by placing a clear shot behind the opponent , and an opponent takes up 
 the ready position in the back section of the court , a drop shot falling near the net is 
 appropriate . during a rally , a player needs to select the most appropriate shot to disrupt 
 an opponent s readiness , and as soon the opponent s readiness disrupted , deliver the most 
 offensive shot to earn a point3 , 4 .
reports about strokes have been made in some previous studies of badminton games , which 
 focused on the development of skills for delivering effective services and overhead 
 strokes5 , 6 , or the characteristics of upper - limb muscle activities of skilled 
 badminton players when hitting a smash7 . 

furthermore , in badminton rallies , quick movements are essential for returning the 
 shuttlecocks at various speeds in all directions . to win a rally , increased leg strength 
 enabling rapidly movement to the spots where the shuttlecock falls8 , and endurance to continue moving without decreasing the 
 speed of movement9 , 10 , are crucial . in addition , in order to effectively return a 
 shuttlecock ( to disrupt an opponent s readiness ) , it is necessary to deliver a stroke in a 
 stable stance . in these situations ,
players need to instantaneously predict the spot where 
 the shuttlecock will fall , and immediately begin to move to it .
however , no studies have 
 examined the mechanisms by which badminton players instantaneously react to shuttlecocks , 
 and move . in which demands , instantaneous lower - limb muscle movements are particularly 
 needed .
if badminton players have the ability to instantaneously activate their own 
 lower - limb muscles , the excitability of their spinal motor neurons controlling the fibers of 
 such muscles may be characteristic .
the soleus h - reflex has frequently been the focus of 
 previous studies11,12,13 , as it is considered to 
 represent the excitability of spinal motor neurons .
accordingly , in line with this , the 
 present study aimed to clarify the characteristics of badminton players motor neuron 
 excitability by examining the soleus h - reflex in the ready position immediately before 
 making a return .
sixteen individuals with experience of playing badminton ( mean age : 20.92.1 ; years of 
 experience : 8.33.0 ) and 16 without such experience ( 20.11.2 ) were studied .
all subjects 
 were provided with explanations regarding the study objectives and its safety before 
 obtaining their consent to voluntarily participate in this .
this study , which was conducted 
 with the approval of the research ethics committee of the health science university 
 ( approval number : 13 ) .
neuropack ( nihon kohden ) was used for the measurement of the m- and h - waves . before 
 measurement
silver plated 
 electrodes for recording were placed on the skin of the medial part of the soleus on both 
 sides , while bipolar stimulating electrodes were attached to the popliteal fossa of the 
 dominant and non - dominant legs .
subsequently , electrical stimulation was intracutaneously 
 applied to the tibial nerves to measure the m- and h - waves in the medial part of the soleus ; 
 and their thresholds and maximum values were recorded by gradually increasing stimulation . 
 for h - wave measurement ,
the stimulation level was set to obtain h - wave amplitudes of 
 approximately 30% of the maximum m - wave value ( mmax ) , as well as the m - wave of 4 to 8% mmax , 
 at a frequency of 0.2  hz14 .
when 
 recording the h - reflex , it was confirmed that the m - wave remained unchanged .
when changes 
 were observed , the recorded values were discarded due to considering the possibility of 
 changes in the stimulation level .
the h - reflex was measured in the ready position before 
 receiving a shuttlecock with or without a racket held in the dominant or non - dominant hand , 
 in addition to a static upright stance .
the subjects were instructed to maintain these 5 
 stances , and the h - wave was recorded 10 times , and the mean was calculated ( fig . 1fig .
1.h - wave after tibial nerve stimulation of stance in a representative badminton 
 subject ) .
h - wave after tibial nerve stimulation of stance in a representative badminton 
 subject among the amplitudes obtained for each stance , the difference between the minimum and 
 maximum h - wave values was calculated .
subsequently , the difference between the minimum and 
 maximum m - wave values ( mmax ) as a response to maximum stimulation in the supine position was 
 calculated to normalize the h - wave value as a percentage of the mmax . for statistics ,
significant differences were 
 examined by performing one - way analysis of variance , followed by multiple comparisons , 
 adopting the tukey - kramer method with a significance level of 5% .
the h - wave rate of each stance was calculated , using the values when just standing as 100% 
 ( table 1table 1.h - wave in the badminton and control groups in each stancebadmintoncontrol significantholdingdominant ( % ) 86.510.5108.615.6*non - dominant ( % ) 91.014.7113.527.8without a racketdominant ( % ) 94.915.2103.316.4non - dominant ( % ) 90.813.397.815.8 * : p<0.05 ) . in the badminton group ,
the h - wave significantly decreased when holding a 
 racket in the dominant hand compared to when standing .
in contrast , in the control group , no 
 significant differences were observed between when standing and the other stances . 

furthermore , the h - wave was suppressed in all stances compared to when standing in the 
 badminton group , while it was promoted in the control group .
muscle stimulation excites type ia afferent fibers , and consequently activates spinal alpha 
 motor neurons , leading to the contraction of stimulated muscles ( stretch reflex ) .
the h - wave 
 obtained with electrical stimulation has been used as an index for evaluating the spinal 
 control of muscle contraction during the stretch reflex , as it represents the excitability 
 of spinal motor neurons . in previous studies ,
the soleus h - wave obtained by eliciting 
 stimuli was shown to be greater when standing compared to walking15 , and this may be explained by the mechanism in which the 
 stretch reflex stabilizes the ankle joint when standing ( increased h - wave ) , while it 
 interferes with the swing phase when walking ( decreased h - wave ) . in short , a greater 
 amplitude of
the h - wave 
 also varies between different exercise tasks , such as walking and running , and stances , such 
 as prone and standing positions16 , 17 .
furthermore , the soleus h - wave has been 
 reported to be greater in swimmers than in non - swimmers18 . on the other hand ,
the h - reflex level is lower in professional 
 ballet dancers than in athletes in general19 .
based on these findings , long - term physical training may 
 specifically influence the excitability of spinal motor neurons . in the present study , on 
 comparison of the soleus h - wave of those with and without experience of playing badminton 

were compared , and its values was significantly lower in the former when experienced players 
 held in the dominant hand , while those with no experience of playng badminton showed a 
 markedly different tendency .
some previous studies reported that the h - wave amplitude is 
 greater in athletes mainly engaged in endurance training than in those mainly engaged in 
 power training20,21,22 .
such training - dependent 
 ( endurance / power ) variation in the h - wave may be associated with differences in the 
 lower - limb loading level .
for example , the h - wave decreases in the prone position compared 
 to when standing under the influence of gravity17 , and increases in a microgravity environment or underwater11 , 23 . in this respect ,
continuous badminton training suppresses the soleus 
 h - wave , presumably due to being power - focused . in badminton games , it is necessary for 
 players to deal with shots at various speeds , such as drop shots near the net and high - speed 
 smashes , and appropriately the return shuttlecocks .
therefore , badminton players need to 
 increase the instantaneous force of their legs to execute rapid movements .
the results of the present study suggest that the excitability of 
 badminton players spinal motor neurons may be suppressed by training to increase the 
 instantaneous force ( power training ) .
furthermore , the reduced excitability of spinal motor 
 neurons when playing badminton may be associated with an increased ability to move to feet 
 rapidly .
considering that badminton is regarded as a lifelong sport for a wide range of age 
 groups , regardless of the sex , and that it increases the stepping ability ( by suppressing 
 the excitability of spinal motor neurons ) , this sport is also likely to be an effective 
 fall - preventing on approach .
 [ purpose ] this study aimed to clarify the characteristics of motor neuron excitability by 
 examining the soleus h - reflex in the ready position adopted immediately before making a 
 return during badminton games . 
 [ subjects ] sixteen individuals with ( badminton group ) and 
 16 without ( control group ) experience of playing badminton were studied . 
 [ methods ] each 
 subject was instructed to take up various stances for returning a shuttlecock to measure 
 the h- and m - waves in the soleus . 
 [ results ] the h - wave was significantly decreased when 
 gripping a racket was held in the dominant hand than compared to just standing in the 
 badminton group . in contrast , in the control group , no significant differences were 
 observed between when standing and the other stances . 
 [ conclusion ] based on these results , 
 the excitability of spinal motor neurons may have been reduced ( h - wave suppression ) by 
 badminton training to increase the instantaneous force ( power training ) . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION