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Effects of Electrical Stimulation of the Calf Muscles
on Jumping Performance
Nagaoka Daichi
1
, Ogiso Kazuyuki
1
, Takenaka Mutsumi
1
and Tokui Masato
2
1
Faculty of education Kogakkan University, Ise, Mie, Japan
2
Department of Sport Science, Kyusyu Kyoritsu University, 1-8 Jiyugaoka, Yahatanishi-ku, Kitakyusyu, Fukuoka, Japan
1 OBJECTIVES
The calf muscles contract almost isometrically while
the Achilles tendon stretches and shortens during the
contact period when walking (Fukunaga et al.,
2001). This interaction between them makes it
possible for the muscles to exert a larger force and
for the tendinous tissue to function as a spring so
that walking can be performed more efficiently. In
addition, jumping requires an even larger force than
walking, and it is likely then that the functions of the
tendinous tissue influence performance
considerably. However, it is difficult to control the
functions of the tendinous tissue during jumping
because it is not innervated by afferent nerves. In
this study, therefore, to investigate the effects of
tendinous tissue on jumping performance, we
induced lengthening and shortening of the Achilles
tendon by forcibly contracting the calf muscles by
electrical stimulation.
2 METHODS
2.1 Subjects
Fifteen healthy men participated in this study (age,
21.1 ± 1.3 years; height, 173.5 ± 7.0 cm; weight,
69.0 ± 10.5 kg). All subjects were in good health,
with no orthopedic or neuromuscular abnormalities.
Subjects were fully informed of the nature and
possible consequences of the study before providing
written informed consent. The experiments were
conducted in accordance with the Declaration of
Helsinki. Approval was obtained from the Ethics
Committee of Kogakkan University.
2.2 Protocol
Subjects were instructed to perform 10 consecutive
two-legged jumps at maximum effort (100% jump)
and at 50% of the maximal jump height (50% jump).
Jumps were performed on a jump-measuring mat
(PH-1260, DKH, Tokyo, Japan) to measure jump
height, ground contact, and flight time. Subjects
were instructed to place both hands on their waist
and reduce ground contact time as much as possible.
Both normal and electrically stimulated jumps were
performed.
An electrical stimulus was applied over the calf
muscle during the jump at a frequency of 20 Hz
(ES20) or 60 Hz (ES60). Six sets of jumps were
performed with intervals of at least 5 min. Electrical
stimulation intensity was set to 20% of the
maximum ankle plantar-flexion torque, using an
electromyography / evoked potential measuring
system (MEB-2306, NIHON KODEN, Tokyo,
Japan). Two anodes and one cathode were placed on
the proximal and distal ends of the triceps surae
muscle, respectively. Reference marks were placed
on the right caput of the ossis metatarsalis V, ankle
joint, knee joint, greater trochanter, acromion,
tragus, and on the top of the subject’s head.
Jumping movements were filmed in the sagittal
plane with a high-speed camera (300 fps; EXLIM-
F1, CASIO, Tokyo, Japan) with 2 reference marks
placed on the ground at an interval of 2 m. The
subjects were questioned about their jump
performance and asked to rate the force required for
the jump and the ease of control on a 5-point scale
(5: very light or easy; 4: light or easy; 3: normal; 2:
heavy or difficult; 1: very heavy or difficult). In
addition, they were questioned about the extent (1:
none to 5: severe) and location of muscle soreness
each day for 6 days after the experiment.
2.3 Data Processing
The reference points in each frame were
automatically digitized (DARTFISH SOFTWARE,
DARTFISH, Fribourg, Switzerland), smoothed, and
converted to real coordinates. The ankle, knee, and
hip joint angles were computed during the ground
contact phase. Distances between the reference mark
Daichi N., Kazuyuki O., Mutsumi T. and Masato T..
Effects of Electrical Stimulation of the Calf Muscles on Jumping Performance.
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2014 SCITEPRESS (Science and Technology Publications, Lda.)