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Eight days KAATSU-resistance training improved sprint but not jump performance in collegiate male track and field athletes


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The purpose of this study was to investigate the effects of short-term KAATSU-resistance training on skeletal muscle size and sprint/jump performance in college athletes. Fifteen male track and field college athletes were randomly divided into two groups: KAATSU (resistive exercise combined with blood flow restriction, n=9) and control (n=6) groups. The KAATSU group trained twice daily with squat and leg curl exercises (20% of 1-RM, 3 sets of 15 repetitions) for 8 consecutive days while both KAATSU and control groups participated in the regular sprint/jump training sessions. Maximal strength, muscle-bone CSA, mid-thigh muscle thickness (MTH), and sprint/jump performance were measured before and after the 8 days of training. The muscle-bone CSA increased 4.5% (p 0.05) in the control group. Quadriceps and hamstrings MTH increased (p 0.05) in the control group. Overall 30-m dash times improved (p 0.05) for either the KAATSU or control groups. These data indicated that eight days of KAATSU-training improved sprint but not jump performance in collegiate male track and field athletes.
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Off-season resistance training is an important part
in the recovery and training process for seasonal
sports athletes. Usually, there is insufficient time for
significant muscle hypertrophy to take place during
the off-season, since most studies have reported that
substantial muscle hypertrophy does not occur until
3-4 months of vigorous resistance training has been
completed (Jones and Rutherford, 1987; Staron et al.,
1994; Abe et al., 2000). It would therefore seem
logical that the development of a more effective and
efficient method to promote muscle hypertrophy, in a
relatively short period of time, would be very
advantageous to coaches and their athletes.
The combination of low-intensity (20% of 1-RM)
resistance training with restricted venous blood flow
to the working muscle, KAATSU-resistance training,
may provide an alternative training method to the
traditional high-intensity (HIT, 80% of 1-RM)
resistance training programs currently being used
(Shinohara et al., 1998; Takarada et al., 2000a). It has
been demonstrated that the magnitude of muscle
hypertrophy is similar between KAATSU-resistance
training and HIT when training frequencies and
volumes are the same (Takarada et al., 2000b).
Interestingly, KAATSU-training does not require long
recovery periods between training sessions due to the
very low mechanical stress and minimal muscle
damage produced when a load of only 20% of 1-RM
is used. Recently, Abe et al. (2004) reported that two
weeks of twice-daily KAATSU-training produces
muscle hypertrophy that was similar in magnitude to
those reported after 3-4 months of the more
traditional HIT programs. However, there are no
published data concerning the effects of KAATSU-
training induced muscle hypertrophy on sports and
exercise performance. Thus the purpose of the
present study was to investigate the effects of short-
term KAATSU-resistance training on skeletal muscle
size and sprint/jump performance in college athletes.
Fifteen male track and field college athletes
(sprinters and jumpers) volunteered to participate in
the present study. All subjects trained regularly 5
days per week in both sprinting/jumping and resistive
exercise training programs. The subjects were
randomly divided into two groups: KAATSU-training
(n=9) and control (n=6) groups. All subjects were
Eight days KAATSU-resistance training improved sprint
but not jump performance in collegiate male track and
field athletes
T. Abe, K. Kawamoto, T. Yasuda, C. F. Kearns, T. Midorikawa, Y. Sato
Int. J. Kaatsu Training Res. 2005; 1: 19-23
The purpose of this study was to investigate the effects of short-term KAATSU-resistance training on
skeletal muscle size and sprint/jump performance in college athletes. Fifteen male track and field
college athletes were randomly divided into two groups: KAATSU (resistive exercise combined with
blood flow restriction, n=9) and control (n=6) groups. The KAATSU group trained twice daily with
squat and leg curl exercises (20% of 1-RM, 3 sets of 15 repetitions) for 8 consecutive days while both
KAATSU and control groups participated in the regular sprint/jump training sessions. Maximal
strength, muscle-bone CSA, mid-thigh muscle thickness (MTH), and sprint/jump performance were
measured before and after the 8 days of training. The muscle-bone CSA increased 4.5% (p<0.01) in
the KAATSU group but decreased 1% (p>0.05) in the control group. Quadriceps and hamstrings
MTH increased (p<0.01) by 5.9% and 4.5%, respectively, in the KAATSU group but did not change in
the control group. Leg press strength increased (9.6%, p<0.01) in the KAATSU group but not (4.8%,
p>0.05) in the control group. Overall 30-m dash times improved (p<0.05) in the KAATSU-training
group, with significant improvements (p<0.01) occurring during the initial acceleration phase (0-10m)
but not in the other phases (10-20m and 20-30m). None of the jumping performances improved
(p>0.05) for either the KAATSU or control groups. These data indicated that eight days of KAATSU-
training improved sprint but not jump performance in collegiate male track and field athletes.
Key words: muscle-bone cross-sectional area, B-mode ultrasound, muscle hypertrophy, sport
Correspondence to:
Dr. T Abe, Department of
Exercise and Sport Science,
Tokyo Metropolitan University,
Tokyo, Japan
See end of article for
authors’ affiliations
informed of the procedures, risks, and benefits, and
signed an informed consent document before
participation. The study was approved by the Tokyo
Metropolitan University Ethics Committee for
Human Experiments.
Training protocol
The KAATSU-training group trained twice per day
(7:00-8:00 and 17:00-18:00) for 8 consecutive days.
After a standard warm-up, subjects performed 3 sets
of 15 repetitions of squat and leg curl exercises at an
intensity of 20% of one repetition maximum (20% of
1-RM). Subjects rested for 30 seconds between sets
and exercises and the routine was kept constant for
the duration of the training period. A specially
designed elastic belt (Sato Sports Plaza Ltd., Tokyo,
Japan) was placed around the most proximal portion
of both legs during the exercise sessions in the
KAATSU-training group (Takarada et al., 2002). The
belt contained a small pneumatic bag along its inner
surface that was connected to an electronic pressure
gauge that monitored the restriction pressure (MPS-
700, VINE, Tokyo, Japan). A cuff pressure of ~240
mmHg was selected for the occlusive stimulus as this
pressure has been suggested to restrict venous blood
flow and cause pooling of blood in capacitance vessels
distal to the cuff, and ultimately reduces arterial blood
flow (Takarada et al., 2000b). On Day 1, the cuff
pressure was set at 160 mmHg and was then
increased by 20 mmHg each day until a final training
cuff pressure of 240 mmHg (Day 5) was reached. The
restriction of muscular blood flow was maintained for
the entire exercise session (including rest periods) and
was released immediately upon completion of the
session. The control group did not perform any
resistive exercises during the present study, however,
both KAATSU and control groups performed regular
sprint/jump training during the study period.
Maximum strength measurements
Maximum dynamic strength (1-RM) was evaluated
prior to (pre-testing), and for two days after the final
training session (post-testing), by using an isotonic leg
press machine (Universal). All subjects were instructed
on proper lifting techniques and allowed to practice.
After a standard warm-up, the leg press load was set
at 80% of the predicted 1-RM. Following each
successful lift the load was increased by 5% until the
subject failed to lift the load through the entire range
of motion. A test was considered valid if the subject
used proper form and completed the entire lift in a
controlled manner without assistance. On average,
six trials were required to complete a 1-RM test.
Approximately 2-3 min of rest was allowed between
each attempt to ensure recovery. One subject in the
control group did not perform the 1-RM strength
testing because of a previous orthopedic problem.
Muscle size measurements
Anthropometry (π[r - (Q-AT + H-AT) / 2]
) was
used to estimate the muscle-bone CSA for the mid-
thigh each morning prior to the training session and
prior to the post-testing. Where r was the radius of
the thigh calculated from mid-thigh girth of the right
leg, and Q-AT and H-AT were ultrasound-measures
of anterior and posterior thigh adipose tissue
thickness, respectively. The estimated coefficient of
variation (CV) of this measurement was 1.5 %.
Muscle thickness (MTH) of the anterior and
posterior mid-thigh was measured using B-mode
ultrasound with a 5 MHz scanning head (SSD-500,
Aloka, Tokyo, Japan). The scanning head was
prepared with water-soluble transmission gel that
provided acoustic contact without depression of the
skin surface. The scanner was placed perpendicular
to the tissue interface at the predetermined marked
sites. MTH was measured directly from the screen
with the use of electronic calipers and was
determined to be the distance from the adipose
tissue-muscle interface to the muscle-bone interface.
Validity of the image reconstruction and distance
measurements was established by comparing the
ultrasonic and manual measurements of tissue
thicknesses using human cadavers (Fukunaga et al.,
1989). The CV of this MTH measurement was 1%
(Abe et al., 1994).
Sprint/jumping performance test
Running and jumping tests were conducted on an
outdoor tartan track. For the 30-m dash, subjects
began from a standing position with a self-start. Time
was measured with an electronic timing system
(nearest 0.01 s, Timing Systems, Brower). Three
consecutive trials, with 2-5 min of recovery between
trials, were performed for each subject. The average
score of the fastest two trials was used for data
analysis. Three different jump tests (standing jump,
standing triple jump, and standing 5-step jump) were
performed using a long-jump pit. Subjects began
each jump with an even stance (i.e. feet shoulder
width apart) and three trials of each jump were
performed with the top score (nearest 1 cm) for each
jumping condition used for data analysis (Table 1).
Statistical Analyses
Results are expressed as means ± standard
deviations (SD) for all variables. Data were analyzed
using a two-way analysis of variance (ANOVA) with
repeated-measures (group and time). When
significant main effects and/or interaction were
observed, post-hoc testing was performed by a paired
t-test. Baseline differences between the KAATSU-
training group and the control group were evaluated
with a one-way ANOVA. Person product correlation
coefficients were calculated between parameters of
Kaatsu training and sprint/jump performance20
interest. Statistical significance was set at p < 0.05.
Baseline measurements
There were no differences (p>0.05) in body mass,
mid-thigh girth, 1-RM strength or sprint/jump
performance times (Table 1), or quadriceps and
hamstrings MTH (Figure 2) between KAATSU and
control groups at pre-testing (Table 1).
Changes in skeletal muscle size
Muscle-bone CSA gradually increased (p<0.01) in
the KAATSU-training group but not in the control
group. The muscle-bone CSA increased 4.5%
(p<0.01) at post-testing for the KAATSU-training
group, while the muscle-bone CSA decreased by 1%
(p>0.05) for the control group (Figure 1). Quadriceps
and hamstrings MTH increased (p<0.01) by 5.9% and
4.5%, respectively, in the KAATSU-training group
but did not change in the control group (Figure 2).
Changes in 1-RM strength and sprint/jump
Leg press strength increased significantly (9.6%,
T. Abe, K. Kawamoto, T. Yasuda, et al. 21
Table 1.
Effects ofKaatsuresistance training on muscle size and sprint/jump performance
Kaatsu-Training Control-Training
Pre Post Pre Post
Standing height (cm) 173.9 ± 5.1 176.8 ± 6.0
Body mass (kg) 66.1 ± 4.0 66.5 ± 3.6 67.6 ± 4.4 67.8 ± 4.9
Mid-thigh girth (cm) 51.8 ± 2.8 52.5 ± 2.7 53.3 ± 1.9 53.3 ± 2.1
Thigh fat thickness (mm) 4.7 ± 1.3 4.2 ± 0.8 4.2 ± 0.8 4.3 ± 0.8
Muscle -bone CSA (cm
) 190 ± 21 198 ± 22 204 ± 15 202 ± 17
Leg press 1RM (kg) 208 ± 70 228 ± 75 208 ± 53 218 ± 62
30-m dash (sec) 4.34 ± 0.14 4.26 ± 0.13 4.25 ± 0.19 4.20 ± 0.16
0-10m dash (sec) 1.95 ± 0.11 1.86 ± 0.08 1.88 ± 0.12 1.83 ± 0.10
10-20m dash (sec) 1.23 ± 0.04 1.23 ± 0.04 1.22 ± 0.05 1.23 ± 0.04
20-30m dash (sec) 1.16 ± 0.04 1.17 ± 0.05 1.15 ± 0.05 1.15 ± 0.04
Standing jump (m) 2.42 ± 0.11 2.43 ± 0.13 2.53 ± 0.15 2.49 ± 0.16
Standing triple jump (m) 7.20 ± 0.29 7.26 ± 0.37 7.51 ± 0.54 7.44 ± 0.43
Standing 5 jump (m) 12.49 ± 0.66 12.47 ± 0.71 13.04 ± 0.81 12.81 ± 0.65
P<0.01, P<0.05 pair-t test
Pre D1 D2 D3 D4 D5 D6 D7 D8 Post 1 Post 2
% Change in Muscle & Bone CSA
Hamstrings MTH (cm)
Kaatsu Control
Quadriceps MTH (cm)
Figure 1
. Percent change in estimated
muscle-bone cross-sectional area (CSA) for
the low-intensity resistance training
combined with restriction of muscular blood
flow (Kaatsu-training, filled symbols) and
control (unfilled symbols) groups measured
before, during (every morning prior to the
training session), and after the training
period. Values are mean ± SD.
Figure 2
. Changes in quadriceps and hamstrings muscle thickness (MTH) for
the low-intensity resistance training combined with restriction of muscular
blood flow (Kaatsu) and control groups measured before (unfilled) and after
(filled) the training period. Values are mean ± SD. **P<0.01 between before
and after training.
p<0.01) in the KAATSU-training group but not
(4.8%, p>0.05) in the control group. There was a
strong correlation between 1-RM leg press strength
and estimated muscle-bone CSA during both pre-
testing (r=0.81, n=14, p<0.01) and post-testing
(r=0.85, n=14, p<0.01) when both groups were
combined. The 1-RM leg press strength per unit
estimated muscle-bone CSA was similar (p>0.05) at
both testing periods.
The overall 30-m dash time improved (p<0.05) in
the KAATSU-training group with the improvement
occurring in the first 10m (p<0.01). Standing jump
correlated (r=-0.82, p<0.01) with 30-m dash time at
pre-testing. None of the three jumping performances
improved (p>0.05) for the KAATSU-training group
and there were no changes (p>0.05) for any of the
sprint/jump performances between pre- and post-
testing for the control-training group.
In the present study we found that eight days of
twice daily KAATSU-training increased estimated
skeletal muscle-bone CSA (4-5%) and 1-RM leg press
strength (10%) in male track and field athletes. The
magnitude of increase in muscle-bone CSA and
strength were relatively small but were consistent
with previously published data (Abe et al., 2004). As
shown in Figure 1, muscle-bone CSA gradually
increased throughout the study in the KAATSU
group and greater muscle hypertrophy may have
occurred if the training was continued as previously
reported. Our subjects were highly trained athletes
and conventional resistance training does not readily
produce muscle hypertrophy and strength gain in this
population (Hakkinen et al., 1987). Therefore our
data suggests that KAATSU-training can provide an
effective hypertrophic stimulus even for well trained
Interestingly, the training subjects in the present
study performed 16 total sessions (two sessions per
day) of KAATSU-training exercise for eight
consecutive days while also performing their normal
sprint/jumping training (training frequency: 5 days
per week). In general, seasonal athletes avoid high-
intensity, high-volume resistance training during the
competitive season in order to avoid over-training.
The optimal training protocol is based on the theory
of “super-compensation” which attempts to generate
the greatest growth stimulus while still allowing for
sufficient rest between exercise sessions (Kraemer,
2000). The combination of a vigorous resistance
training program in combination with a sprint/jump
training program can lead to poor event performance
since athletes do not have sufficient recovery time
between training sessions. However, KAATSU-
training at an intensity of 20% of 1-RM produces a
strong hypertrophic stimulus with only minimal
muscle damage (Takarada et al., 2000a), therefore
less recovery time is required. The data from the
present study demonstrated that KAATSU-training
can be combined with regular season training to
provide an effective and efficient method for muscle
hypertrophy in seasonal sports athletes without a loss
of performance.
Sprint running is usually divided into three phases:
initial acceleration (0-10 m), achieving maximal
speed (10-40 m), and maintenance of maximal speed
(40~ m) with each phase corresponding to specific
physical abilities. Our findings indicated that muscle
hypertrophy and strength gain induced by KAATSU-
training resulted in an improved 30-m dash time,
especially during the first 10m (0-10m). These data
are consistent with previous studies. For example,
Delecluse et al. (1995) selectively altered the first
and/or second phases of maximal sprinting
performance by using different types of strength
training. In that study, high-intensity resistance
training resulted in an improved initial acceleration
(first phase) while high-velocity plyometric training
(unloaded) improved the rate at which maximal
speed was reached (second phase). Additionally,
relative muscle strength (e.g., maximal dynamic
strength per body mass) has been related to sprint
starting ability, measured between 0 and 2.5 m,
during a maximal 50-m sprint (Young et al., 1995).
Taken together with the present study, these data
suggest that the initial acceleration phase of sprinting
can be improved by increasing muscle strength.
Previous KAATSU-training studies (Takarada et al.,
2000b and 2002) suggest that in spite of the low level
of force generation during KAATSU-training, a large
number of fast-twitch muscle fibers are recruited and
experience hypertrophy (Yasuda et al., 2004). The
moderate muscle hypertrophy and strength gains of
the present study, however, were not sufficient to
improve jumping performance. Studies that have
demonstrated strength training induced
improvements in jumping performance have
reported much larger gains in muscle size and
strength (Maffiuletti et al., 2000; Bruhn et al., 2004).
It may be that longer KAATSU-training may cause
larger muscle hypertrophy which might then be able
to improve jumping performance. To date, no such
studies have been conducted.
In conclusion, eight days of twice-daily KAATSU
training increased skeletal muscle-bone CSA and
maximal strength. The gains in skeletal muscle-bone
CSA and strength resulted in an improved 30-m
sprint performance, especially during the initial
acceleration phase. Therefore, we have concluded
that KAATSU-training can be performed together
with regular season training in order to provide an
effective and efficient method for enhanced muscle
hypertrophy without a loss in performance.
Kaatsu training and sprint/jump performance22
The authors thank the athletes who participated in this study. We
also thank the Sato Kaatsu Training Research Foundation for their
generous support.
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Authors’ affiliations
T. Abe, T. Yasuda
T. Midorikawa
, Department of Exercise and
Sport Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa,
Hachioji, Tokyo, Japan
K. Kawamoto
, Department of Sports Science, Fukushima University,
Fukushima, Japan
C. F. Kearns
, Cardiovascular/Endocrine Biology, Schering-Plough
Research Institute, NJ, USA
Y. Sato
, Department of Ischemic Circulatory Physiology, The University
of Tokyo, Tokyo, Japan
T. Abe, K. Kawamoto, T. Yasuda, et al. 23
... It is generally accepted that high-intensity resistance training (≥70% of 1RM) can stimulate gains in muscle strength (22). However, previous studies have shown that low-load BFR resistance and endurance exercises performed with BFR can increase maximal strength (28,31,(37)(38)(39)(40). The results of the present study are consistent with previous research in that the leg with BFR exercise showed increased muscle strength. ...
... Walking and cycling with BFR can also positively influence maximal strength (28,31,40,44) According to recent metaanalysis, training with BFR can more effectively improve strength and hypertrophy than low-load training performed with unrestricted blood flow (45). Furthermore, previous findings suggest that significant muscle development is possible in athletes after low-load training with BFR (37)(38)(39). Although evidence suggests that high-intensity exercise without BFR provides a more neurological stimulus than low-intensity resistance exercise with BFR (46,47), well-trained athletes show limited potential for further neural adaptations (48). ...
... Both asymmetry of muscle strength between limbs (55) and leg dominance (injuries occurred more often in the nondominant leg) (56)(57)(58) are risk factors for injuries in skiers. Previous studies reported that the enhancing metabolic stimuli produced by high-frequency BFR training may promote muscle hypertrophy in a very short term (26,38,59,60). In addition, it is suggested that optimal hypertrophy may comprise maximizing the combination of mechanical and metabolic stimuli (22). ...
Full-text available
Purpose: The effects of short-term blood flow restriction (BFR) exercise on muscle blood flow perfusion and performance during high-intensity exercise were determined in elite para-alpine standing skiers to assess whether this would be an effective training regimen for elite athletes with disabilities. Methods: Nine national-level para-alpine standing skiers (mean age, 20.67 ± 1.34 y; four women) were recruited. Non-dominant lower limbs were trained with BFR (eight in final analyses); dominant lower limbs without BFR (seven in final analyses). The 2-week protocol included high-load resistance, local muscle endurance (circuit resistance training), and aerobic endurance (stationary cycling) training performed 4 times/wk, with BFR during local muscle endurance and aerobic endurance sessions. Muscle strength was measured by maximal voluntary isometric contraction (MVIC) in the knee extensors; microcirculatory blood perfusion (MBP), by laser doppler blood flow; and muscle strength and endurance, by the total amount of work (TW) performed during high-intensity centrifugal and concentric contractions. Results: BFR significantly increased absolute and relative MVIC (P < 0.001, P = 0.001), MBP (P = 0.011, P = 0.008), and TW (P = 0.006, P = 0.007) from pretraining values, whereas only absolute MVIC increased without BFR (P = 0.047). However, the MVIC increase with BFR exercise (35.88 ± 14.83 N·m) was significantly greater (P = 0.040) than without BFR exercise (16.71 ± 17.79 N·m). Conclusions: Short-term BFR exercise significantly increased strength endurance, muscle strength, and microcirculatory blood perfusion in national-level para-alpine standing skiers. Our study provides new evidence that BFR exercise can improve local muscle blood perfusion during high-intensity exercise and informs BFR exercise strategies for athletes with disabilities.
... 근육 표면에 가해지는 압력은 운동 효과를 극대화할 수 있다 [1]. 이러한 근압박은 근육으로의 동맥 유입 (arterial inflow)을 부분적으로 감소시키지만, 근육으로 부터 정맥 유출(venous outflow)을 일시적으로 크게 제 한함으로써 [2], 운동 시 골격근의 근비대와 근력을 증가 시키는 효과를 가져온다 [3]. ...
... 일례로, 1주간의 가압 운동 (kaatsu training)은 중년 남성의 대퇴사두근 근단면적 (muscle cross-sectional area)과 근육량(muscle volume)을 각각 3.5%와 4.8% 늘렸고 [4], 6주간의 저 부하 혈류제한운동(low-load vascular restriction training)은 고강도 저항운동(80% 1-RM) 프로토콜과 유사하게 노년 남성의 하지근력을 증가시켰다 [5]. 이러한 처치는 운동 중 압박된 근육의 생리적 반응 수준(즉, circulation)을 높여 [6], 운동능력을 향상하는데 효율적 인 방법으로 여겨진다 [1]. [7,8]. ...
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The physical benefits of wearing compression garments vary, but the effect of compression garment fabrics on lower extremity muscle contraction properties is unknown. The purpose of this study was to determine this effect and to reveal the interaction effect between the compression garments fabrics and the lower extremity muscles. Sixteen young men took part in this experiment. Participants wore compression garments composed of four fabrics of the same size in random order. Six lower extremity muscles were measured using a tensiomyography (TMG), and five muscle contraction properties were collected. There was a significant difference in the muscle contraction properties of each of the lower extremity muscles (p < .05), but there was no significant difference in lower extremity muscle contraction properties based on variations in the compression garment fabrics (p > .05). In addition, there was no interaction between the compression garment fabrics and the lower extremity muscles (p > .05). In conclusion, a variation in the compression garment fabrics of the same compression intensity did not directly affect the muscle contraction properties. Therefore, it is necessary to consider various other settings, such as the design and intensity of compression garments in future studies.
... 22 However, the vast BFR literature also includes 45 repetitions per set to volitional failure protocols. 1,12,16,17 This training method seems to be very complicated and more research is needed to apply BFR safely. Therefore, this paper aims to provide an evidence-based review of existing literature and shed light on sports scientists, strength and conditioning coaches, and physiotherapists as to how to apply resistance exercise with BFR safely. ...
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Low-load resistance exercise with blood flow restriction has been known to stimulate muscle development that is comparable to conventional High-load Resistance Exercise. Resistance exercise with blood flow restriction is a pretty new training technique that can be an option to High-load Resistance Exercise for increasing muscle mass and strength not only in athletes but also in healthy people and elderly people, or rehabilitation for injured athletes with load restrictions. This brief review study aims to summarize the existing literature concerning the basic principles of resistance exercise with blood flow restriction and to provide a brief description of blood flow restriction training to maximize strength and hypertrophy. Blood flow restriction training can be performed when High-load Resistance Exercise is not tolerated because of pain or other contraindications such as absolute weight-bearing restrictions, for instance after surgical procedures to regain strength and muscle mass. High-load Resistance Exercise is associated with high mechanical tension, however, in some cases, this is not warranted. In these cases, resistance exercise with blood flow restriction seems to be a better option. Consequently, blood flow restriction training should not replace High-load Resistance Exercise for the general public or uninjured athletes, but blood flow restriction training can be used as an alternating training tool or in situations where High-load Resistance Exercise is inadvisable.
... Meanwhile, even though many studies have reported the effects of training with LL-BFRE on muscular strength and hypertrophy (Pearson and Hussain, 2015), the evidence of LL-BFRE's influence on power or jumping performance is unclear. Some authors have reported that LL-BFRE or jumping exercises with blood flow restriction in the legs did not affect the power or jumping performance (Abe et al., 2005;Horiuchi et al., 2018). Conversely, Cook et al. (2014) found that three weeks of BFR training with moderate-load (i.e., 70% 1 RM) induced significant increases in strength and countermovement jump performance in young adult rugby players (Cook et al., 2014). ...
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To investigate the effects of implementing low-load blood flow restriction exercises (LL-BFRE) instead of high-load exercises (HL-RE) in a contrast training program on high-level young athletes’ strength and power performance. Fifteen high-level pre-pubescent trampoline gymnasts (national level, Tanner Stage Ⅱ, intermediate experience in strength training) were divided into two groups to complete the same structure of a ten-week contrast strength training program differing only in the configuration of the first resistance exercise of the contrast sequence. The LL-BFRE group (n=7, four girls, 13.94 ± 0.42 y) performed the first resistance exercise of the contrast with LL-BFRE (20% to 30% 1RM, perceived pressure of 7 on a scale from 0 to 10). The HL-RE group (n=8, four girls, 13.83 ± 0.46y) trained the first resistance exercise of the contrast sequence with moderate-to-high load (60% to 85% 1RM). Before and after the training period, isometric mid-thigh pull (IMTP), squat jump (SJ), countermovement jump (CMJ), and drop-jump (DJ) were performed to evaluate the effect of the intervention on strength and power capacities as primary outcomes. Changes in participants’ anthropometric measures, muscle mass, left and right thigh girth, IMTP relative to bodyweight (IMTP-R), eccentric utilization ratio (EUR), and reactive strength index (RSI) were assessed as secondary outcomes. There was no significant interaction (p >0.05) between group x time in any power and strength outcome, although SJ and EUR showed a trend to significant interaction (p=0.06 and p=0.065, respectively). There was an overall effect of time (p <0.05) in all power and strength variables (CMJ, SJ, EUR, DJ, RSI, IMTP, and IMTP-R). There was a significant interaction in muscle mass (MM) (β = 0.57 kg, 95% CI = [0.15; 0.98], t13 = 2.67, p = 0.019), revealing that participants in LL-BFRE increased their muscle mass (6.6 ±3.1%) compared to HL-RE (3.6 ±2.0%). Anthropometric variables did not present any group or interaction effect, however, there was a time effect (p <0.05). Implementing LL-BFRE in place of HL-RE as a conditioning activity in a contrast training sequence might be equally effective in improving lower-body strength and power in preadolescent trampoline gymnasts.
... In recent years, research has demonstrated that combining of low-load resistance training with BFR to the active musculature may produce significant hypertrophy and strength gains [15][16][17][18] using loads as low as 30% 1RM [19]. In addition BFR training has been found to yield hypertrophy responses comparable to that observed with heavy-load resistance training [20]. ...
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Background and purpose Numerous research studies have shown the effects of Blood Flow Restriction (BFR) training on muscle strength and hypertrophy, but there is still no comprehensive analysis of the effects on aerobic capacity. The purpose of this study was to conduct a systematic review with meta-analysis to evaluate the qualitative and quantitative results of BFR training on aerobic capacity. Methods PRISMA guidelines were used to carry out the systematic review and meta-analysis. Five electronic databases were searched up to October 2020: PubMed, Web of Science, EBSCO, Scopus and Cochrane/Embase. Data selected for primary analysis consisted of post-intervention changes in VO2 values (VO2max, VO2peak). Case reports, acute studies and review studies were excluded. The protocol was registered on PROSPERO (CRD42020214919). Results After the elimination of duplicates, 62 records were screened. Among these, 17 studies were included in the systematic review. Twelve of these were involved in the meta-analysis. Discussion BFR training compared with exercise under normal blood flow conditions could positively influences both aerobic capacity and athletic performance. Differences in young and older subjects were discussed. BFR showed to be a promising and beneficial training to elicit improvements in aerobic capacity (measured in VO2) and performances. Level of evidence 1a.
... This is accomplished by wrapping a restrictive bandage or specially designed pressure belts around the limb while doing dynamic exercise. This bandage is wrapped on the top point of the extremity where the muscle to be exercised [13,14]. When this type of exercise is combined with low intensity, it promotes muscle hypertrophy and provides various performance enhancements [15,16,17]. ...
Introduction. The aim of this study was to understand the effect of blood flow restriction (BFR) and plyometric training methods on the development of taekwondo technical kick force in active taekwondo athletes. Material and Method. 31 taekwondo athletes, aged between 15 and 18 years, voluntarily participated in the study. They were divided into the blood flow restriction, plyom-etric training and control groups. In addition to taekwondo training, blood flow restriction and plyometric training group were trained for 6 weeks. Technical strike force measurements were made with Herman Digital Trainer, placed on the Hasedo. The difference was examined by the paired sample t-test. Comparison of three groups was made with a use of the Friedman test. Re-sults. Statistically significant pre- and post-test differences were found in all technical impact strength values except Tolyochagi right leg in groups participating in BFR training. The difference in the right and left foot and palding kick, the right foot tolyochagi kick, and the right-left foot dwitchagi stroke was statistically significant only in the BFR training group. Conclusions. Con-sidering the effective development of the BFR method on technical strike force in Taekwondo athletes, it is thought that adding the BFR method to routine taekwondo training under the su-pervision of an expert will positively contribute to success.
... Previous research that has used plyometric training as part of their strength training protocols have found contrasting results. For instance, Abe et al. [32] reported that local hypoxia during strength training did not have any effect on jump performance, similarly Álvarez-Herms et al. [2] also observed no significant change in SJ and in CMJ after 4 weeks strength training in a hypoxic compared to normoxic environment. However, in a study conducted by Brocherie et al. [3] 5 weeks of repeated sprint training in hypoxia (2900 m), also involving plyometric exercises, showed greater increases in CMJ height compared to the group training in normoxia, along with a significant increase in lower-limb explosive power in both groups [3]. ...
Strength training in hypoxia has been shown to enhance hypertrophy and function of skeletal muscle, however, the effects of plyometric training in hypoxia is relatively unknown. Therefore, this study aimed to examine the effects of plyometric training in hypoxia compared to normoxia on body composition, sprint and jump parameters. Twenty-three male physical education students (20.4±2.0 years, mean±SD) participated in the study and were divided into a plyometric training in hypoxia (PTH, n=8), plyometric training in normoxia (PTN, n=7) or control group (C, n=8). The PTH group trained in normobaric hypoxia (approximately 3536 m) 3 days/week for 8 weeks, while the PTN trained in normoxia. PTH induced significant improvements from baseline to post-testing in countermovement-jump (37.8±6.7 cm, 43.4±5.0 cm, p<0.05), squat-jump (35.4±6.2 cm, 41.1±5.7 cm, p<0.05), drop-jump height (32.8±6 cm, 38.1±6 cm, p<0.05) and 20-m sprint performance (3257.1±109.5 ms, 3145.8±83.6 ms, p<0.05); whereas PTN produced significant improvement only in countermovement-jump (37.3±4.8 cm, 40.5±4.5 cm, p<0.05) and 20-m sprint performance (3209.3±76.1 ms, 3126.6±100.4 ms, p<0.05). Plyometric training under hypoxic conditions induces greater improvement in some jump measures (drop-jump and squat-jump) compared to similar training in normoxia.
... Bu sonuca istinaden, iskemik ön koşullandırmanın orta yoğunlukta yapılan egzersizlerde kas deoksijenasyon dinamiklerini, şiddetli egzersizlerde ise dayanıklılık gelişimini hızlandırdığını bildirmişlerdir. (54) Kraus ve arkadaşları (2015), uzaktan iskemik ön koşullandırmanın anaerobik kapasite üzerine olan etkilerini incelemek amacıyla yaptıkları çalışmada, 1. grup için 6 erkek, 8 kadın denek belirlemiş (n:14), 2. grup için ise 21 erkek, 8 kadın denekle (29) çalışılmıştır. Çalışmada, iskemik ön koşullandırma, denekler sırt üstü yatar pozisyonda manşetler sol üst kola tek taraflı, bilateralde aynı anda sağ ve sol kola 5dk basınç uygulama, 5dk gevşetme olarak 4 tekrarlı olarak, 2dk'lık pasif dinlenme ile 4x30sn'lik Wingate testini tamamlamışlardır. ...
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Kalp-damar sistemi, doku veya organların işlevlerini kontrol edilebilmek için gerekli olan kan ihtiyacını karşılaması gerekmektedir. Bu ihtiyacın karşılanması sırasında yaşanacak olan denge ve kesinti sorunları ilgili doku ya da organdaki işlev bozukluğuna yol açarak iskemi durumunu ortaya çıkarmaktadır. Bu durumda yaşanan oklüzyon-reperfüzyon durumu (kan akımı kısıtlama ve tekrar serbestleme / yetersizlik-kanlanma) bazı doku-organ hasarlarına sebebiyet verebilmektedir. Aynı zamanda, yaşanan bu evrede bazı metabolit oluşumları nedeniyle farklı dokularda da negatif yönde etkilenmeler ortaya çıkabilmektedir. (1) İskemik ön koşullandırma (kalp kası üzerinde) ilk olarak 1986 yılında uygulanmıştır. (2) Kalp kasında (miyokard), kalbi besleyen damarların (koroner) oklüzyonu (40 dakikalık) öncesi, reperfüzyon aralıkları (5’ er dakikalık) düzenlenerek ilgili damarların tıkanması sonucunda hücrelerdeki ölüm (nekroz) oranı (yaklaşık %75) oldukça azalmıştır. (3,4) İskemik ön koşullandırmada deneyi; hayvanlarda (köpek) yapılan, ölümcül olmayan, kardiyak iskemi-reperfüzyon aralıklarının daha sonra uzun süreli kardiyak iskemiye karşı koruma sağladığını gösteren bir deneydir. Kısa aralıklı oklüzyon-reperfüzyon döngülerine ve ardından hiperemiye maruz kalmadan oluşan iskemik ön koşullandırmanın (iskemik preconditioning / IPC) dokuları iskemiye karşı koruduğu kanıtlanmıştır. (2)
Blood flow restriction (BFR) therapy is being used more frequently for rehabilitation from orthopedic injuries. Several physiologic mechanisms of action, at local and systemic levels, have been proposed. Numerous studies have investigated the effects of BFR training in healthy athletes; however, limited clinical data exist supporting the use of BFR after surgery. Given that BFR training may facilitate muscle development using low-load resistance exercises, it offers a unique advantage for the post-surgical patient who cannot tolerate traditional high resistance training. [Orthopedics. 2021;44(6):xx-xx.].
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SUMMARY Purpose: The overarching aim of this thesis was to investigate the effect of short-term blocks with high-frequency low-load blood flow restricted resistance exercise (BFRRE) on muscular adaptations in untrained individuals, recreationally trained individuals and elite strength athletes. Three independent studies with four original papers have been completed towards this objective. High-frequency BFRRE has been shown to induce rapid muscle growth accompanied by increased numbers of satellite cells and myonuclei. However, the satellite cell and myonuclear responses appears to plateau after an initial block of training and it may be speculated that a rest period can reset the responsiveness of the system after the initial training response. Thus, the aims of Study I and II were to investigate the effect and time-course of changes in fiber and whole muscle areas, myonuclear and satellite cell numbers and muscle strength during two five-day blocks of high-frequency low-load BFRRE, separated by 10 days of rest. In addition, the importance of performing BFRRE sets to failure on cellular adaptations has not been investigated. Therefore, Study II compared the effect of a failure- vs. a non-failure high-frequency BFRRE protocol. Despite the impressive rates of muscle growth reported in some studies on high-frequency BFRRE, several recent studies have shown that BFRRE increases markers of muscle damage and cellular stress. To shed light on possible mechanisms for myocellular stress and damage after strenuous high-frequency BFRRE, heat shock protein (HSP) responses, glycogen content and inflammatory markers were investigated in Study I (paper II). Finally, the impact of low-load BFRRE has not yet been investigated in highly specialized strength athletes, such as powerlifters. Thus, the aim of Study III was to investigate the effect of implementing two five-day blocks of high-frequency low-load BFRRE during six weeks of periodized strength training in elite powerlifters, on the changes in number of satellite cells, myonuclei and muscle size and strength. METHODS: A total of 47 healthy men and women participated in the studies. Thirteen recreationally trained sports students in Study I (24±2 yrs [mean±SD], 9 men) and 17 untrained men in Study II (25±6 yrs), completed two 5-day-blocks of seven BFRRE sessions, separated by a 10-day rest period. A failure BFRRE protocol consisting of four sets with knee extensions to voluntary failure at 20% of one-repetition maximum (1RM) was performed with both legs in Study I, and randomized to one of the legs in Study II. The other leg in Study II performed a non-failure BFRRE protocol (30, 15, 15, 15 repetitions). In Study I, muscle samples from m. vastus lateralis (VL) obtained before and 1h after the first session in the first and second block (“Acute1” and “Acute2”), after three sessions (“Day4”), during the “Rest Week”, and at three (“Post3”) and ten days post-intervention (“Post10”), were analyzed for muscle fiber area (MFA), myonuclei, satellite cells, mRNA, miRNA, HSP70, αB-crystallin, glycogen (PAS staining), CD68+ (macrophages) and CD66b+ (neutrophils) cell numbers. Muscle strength (1RM knee-extension) and whole muscle size (ultrasonography and magnetic resonance imaging) was measured up until 20 days after the last exercise session (Post20). In Study II, muscle samples obtained before, at midtraining, and 10 days post-intervention (Post10) were analyzed for muscle fiber area (MFA), myonuclei, and satellite cells. Muscle thickness, cross-sectional area and echo intensity were measured by ultrasonography, and knee-extension strength with 1RM and maximal isometric contraction (isomMVC) up until Post24. In Study III, seventeen national level powerlifters (25±6 yrs, 15 men) were randomly assigned to either a BFRRE group (n=9) performing two blocks (week 1 and 3) of five BFRRE front squat sessions within a 6.5-week training period, or a conventional training group (Con; n=8) performing front squats at ~70% of 1RM. The BFRRE consisted of four sets (first and last set to voluntary failure) at ~30% of 1RM. Muscle biopsies were obtained from VL and analyzed for MFA, myonuclei, satellite cells and capillaries. Cross-sectional areas (CSA) of VL and m. rectus femoris (RF) were measured by ultrasonography. Strength was evaluated by maximal voluntary isokinetic torque (dynMVC) in knee-extension and 1RM in front squat. RESULTS: With the first block of BFRRE in Study I (paper I), satellite cell number increased in both fiber types (70-80%, p<0.05), while type I and II MFA decreased by 6±7% and 15±11% (p<0.05), respectively. No significant changes were observed in number of myonuclei or strength during the first block of training. With the second block of training, muscle size increased by 6-8%, while the number of satellite cell (type I: 80±63%, type II 147±95%), myonuclei (type I: 30±24%, type II: 31±28%) and MFA (type I: 19±19%, type II: 11±19%) peaked 10 days after the second block of BFRRE. Strength peaked after 20 days of detraining (6±6%, p<0.05). Pax7- and p21 mRNA expression were elevated during the intervention, while myostatin, IGF1R, MyoD, myogenin, cyclinD1 and -D2 mRNA did not change until 3-10 days post intervention. In paper II of Study I, αB-crystallin was reported to translocate from the cytosolic to the cytoskeletal fraction after Acute1 and Acute2 (p<0.05), and immunostaining revealed larger responses in type 1 than type 2 fibers (Acute1, 225±184% vs. 92±81%, respectively, p=0.001). HSP70 was increased in the cytoskeletal fraction at Day4 and Post3, and immunostaining intensities were more elevated in type 1 than in type 2 fibers (Day4, 206±84% vs. 72±112%, respectively, p<0.001). Glycogen content was reduced in both fiber types; but most pronounced in type 1, which did not recover until the Rest Week (-15-29%, p≤0.001). Intramuscular macrophage numbers were increased by ~65% postintervention, but no changes were observed in muscle neutrophils. Both protocols in Study II increased myonuclear numbers in type-1 (12- 17%) and type-2 fibers (20-23%), and satellite cells in type-1 (92-134%) and type-2 fibers (23-48%) at Post10 (p<0.05). RF and VL size increased by 7-10% and 5-6% in both legs at Post10 to Post24, whereas the MFA of type-1 fibers in Failure was decreased at Post10 (-10±16%; p=0.02). Echo intensity increased by ~20% in both legs during Block1 (p<0.001) and was ~8-11% below baseline at Post24 (p=0.001-0.002). IsomMVC decreased by 8-10% in both legs and 1RM by 5% in the failure leg after Block1 (p=0.01-0.02). IsomMVC and 1RM were increased in both legs by 6-7% and 9-11% at Post24, respectively (p<0.05). In Study III, BFRRE in powerlifters induced selective type I fiber increases in MFA (BFRRE: 12% vs. Con: 0%, p<0.01) and myonuclear number (BFRRE: 17% vs. Con: 0%, p=0.02). Type II MFA was unaltered in both groups. BFRRE induced greater changes in VL CSA than control (7.7% vs. 0.5%, p=0.04), and the VL CSA changes correlated with the increases in MFA of type I fibers (r=0.81, p=0.02). No significant group differences were observed in SC and strength changes. CONCLUSIONS: High-frequency low-load BFRRE in Study I and II induced pronounced responses in satellite cell proliferation, delayed myonuclear addition and increases in muscle size, concomitantly with delayed increases in strength in untrained and recreationally trained individuals. While the gains in satellite cell and myonuclear numbers as well as muscle size and strength were similar between non-failure and failure BFRRE protocols in Study II, perceptions of exertion, pain and muscle soreness were lower in the non-failure leg. Hence, nonfailure BFRRE may be a more feasible and safe approach. However, we report that short-term strenuous high-frequency BFRRE can induce elevations in multiple markers of cellular stress and damage in non-strength trained individuals. We showed that low-load BFRRE stressed both fiber types, but the fiber type-specific HSP-responses and prolonged glycogen depletion strongly indicated that type 1 fibers were more stressed than type 2 fibers. It appears that the first block of unaccustomed BFRRE exceeded the capacity for recovery in both Study I and II, and may have induced muscle damage in some of our participants. In accordance with our hypothesis, our participants seemed to recover during the rest week and to respond well to the second block of BFRRE. It is intriguing that BFRRE induced preferential type I hypertrophy after the second block of training in Study I. This indicates that although the initial stress may be too high (and cause damage), adaptive responses will occur and later the same exercise stress will be the important stimuli for adaptation. Our findings from Study I and II may provide insights into some of the physiological mechanisms underpinning overreaching and subsequent recovery and supercompensation after periods of very strenuous exercise. Finally, in Study III, two one-week blocks with high-frequency low-load BFRRE implemented during six weeks of periodized strength training induced a significant increase in muscle size and myonuclear addition in elite powerlifters. Preferential hypertrophy and myonuclear addition of type I fibers appears to explain most of the overall muscle growth. Intriguingly, these responses are in contrast to heavy-load strength training, that typically induces a greater type II fiber hypertrophy. Consequently, BFRRE appears to have complementary effects to heavyresistance training and the combination of these two methods may optimize adaptations of both fiber types in highly strength-trained individuals. However, despite the increases in muscle size, we could not observe any group differences in maximal strength.
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This study investigated the effects of twice daily sessions of low-intensity resistance training (LIT, 20% of 1-RM) with restriction of muscular venous blood flow (namely "LIT-Kaatsu" training) for two weeks on skeletal muscle size and circulating insulin-like growth factor-1 (IGF-1). Nine young men performed LIT-Kaatsu and seven men performed LIT alone. Training was conducted two times / day, six days / week for 2 weeks using 3 sets of two dynamic exercises (squat and leg curl). Muscle cross-sectional area (CSA) and volume were measured by magnetic resonance imaging at baseline and 3 days after the last training session (post-testing). Mid-thigh muscle-bone CSA was calculated from thigh girth and adipose tissue thickness, which were measured every morning prior to the training session. Serum IGF-1 concentration was measured at baseline, mid-point of the training and post-testing. Increases in squat (17%) and leg curl (23%) one-RM strength in the LIT-Kaatsu were higher (p<0.05) than those of the LIT (9% and 2%). There was a gradual increase in circulating IGF-1 and muscle-bone CSA (both p<0.01) in the LIT-Kaatsu, but not in the LIT. Increases in quadriceps, biceps femoris and gluteus maximus muscle volume were, respectively, 7.7%, 10.1% and 9.1% for LIT-Kaatsu (p<0.01) and 1.4%, 1.9% and -0.6% for LIT (p>0.05). There was no difference (p>0.05) in relative strength (1-RM / muscle CSA) between baseline and post-testing in both groups. We concluded that skeletal muscle hypertrophy and strength gain occurred after two weeks of twice daily LIT-Kaatsu training.
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The purpose of this study was to investigate the relationship between strength measures and sprinting performance, and to determine if these relationships varied for different phases of sprint running. Twenty (11 males and 9 females) elite junior track and field athletes served as subjects. Athletes performed maximum sprints to 50 m from a block start and time to 2.5, 5, 10, 20, 30, 40 and 50 m were recorded by electronic timing gates. The resultant forces applied to the blocks were obtained from two force platforms. Twenty-seven measures of strength and speed-strength (absolute and relative to bodyweight) were collected from the height jumped and the force-time curve recorded from the takeoff phase of vertical jumping movements utilizing pure concentric, stretch shortening cycle (SSC) and isometric muscular contractions. Pearson correlation analysis revealed that the single best predictor of starting performance (2.5 m time) was the peak force (relative to bodyweight) generated during a jump from a 120 degree knee angle (concentric contraction) (r = 0.86, p = 0.0001). The single best correlate of maximum sprinting speed was the force applied at 100 ms (relative to bodyweight) from the start of a loaded jumping action (concentric contraction) (r = 0.80, p = 0.0001). SSC measures and maximum absolute strength were more related to maximum sprinting speed than starting ability. It was concluded that strength qualities were related to sprinting performance and these relationships differed for starting and maximum speed sprinting.
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An 8-wk progressive resistance training program for the lower extremity was performed twice a week to investigate the time course for skeletal muscle adaptations in men and women. Maximal dynamic strength was tested biweekly. Muscle biopsies were extracted at the beginning and every 2 wk of the study from resistance-trained and from nontrained (control) subjects. The muscle samples were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain content. In addition, fasting blood samples were measured for resting serum levels of testosterone, cortisol, and growth hormone. With the exception of the leg press for women (after 2 wk of training) and leg extension for men (after 6 wk of training), absolute and relative maximal dynamic strength was significantly increased after 4 wk of training for all three exercises (squat, leg press, and leg extension) in both sexes. Resistance training also caused a significant decrease in the percentage of type IIb fibers after 2 wk in women and 4 wk in men, an increase in the resting levels of serum testosterone after 4 wk in men, and a decrease in cortisol after 6 wk in men. No significant changes occurred over time for any of the other measured parameters for either sex. These data suggest that skeletal muscle adaptations that may contribute to strength gains of the lower extremity are similar for men and women during the early phase of resistance training and, with the exception of changes in the fast fiber type composition, that they occur gradually.
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To investigate the efficacy of ischemia in strength training with low mechanical stress, tourniquet ischemia was utilized in low-resistance training. Five untrained subjects conducted one-legged isometric knee extension training with one leg ischemic (I-leg) and the other non-ischemic (NI-leg). Repeated isometric contractions for 2 s with 3 s relaxation in between were continued for 3 min and conducted 3 days/week for 4 weeks as training. Training resistance was 40% of maximal voluntary contraction (MVC) of respective leg and tourniquet ischemia was applied during I-leg training. MVC in I-leg after 2 weeks (9% gain) and 4 weeks (26% gain) were significantly higher than pre-training value (p < 0.05). A significant increase in maximal rate of torque development in I-leg was observed after 4 weeks (p < 0.05). On the contrary, there was no significant changes in either of the parameters in NI-leg. As a consequence, the differences between legs for both parameters were significant after 2 and 4 weeks (p < 0.05 or p < 0.01). The substantial gain in strength and maximal rate of torque development in I-leg demonstrated the efficacy of tourniquet ischemia during low-resistance training of short duration, and suggested the importance of neuromuscular and/or metabolic activity, other than high mechanical stress, to the adapting responses to strength training.
1. Increases in strength and size of the quadriceps muscle have been compared during 12 weeks of either isometric or dynamic strength training. 2. Isometric training of one leg resulted in a significant increase in force (35 +/- 19%, mean +/- S.D., n = 6) with no change in the contralateral untrained control leg. 3. Quadriceps cross-sectional area was measured from mid-thigh X-ray computerized tomography (c.t.) scans before and after training. The increase in area (5 +/- 4.6%, mean +/- S.D., n = 6) was smaller than, and not correlated with, the increase in strength. 4. The possibility that the stimulus for gain in strength is the high force developed in the muscle was examined by comparing two training regimes, one where the muscle shortened (concentric) and the other where the muscle was stretched (eccentric) during the training exercise. Forces generated during eccentric training were 45% higher than during concentric training. 5. Similar changes in strength and muscle cross-sectional area were found after the two forms of exercise. Eccentric exercise increased isometric force by 11 +/- 3.6% (mean +/- S.D., n = 6), and concentric training by 15 +/- 8.0% (mean +/- S.D., n = 6). In both cases there was an approximate 5% increase in cross-sectional area. 6. It is concluded that as a result of strength training the main change in the first 12 weeks is an increase in the force generated per unit cross-sectional area of muscle. The stimulus for this is unknown but comparison of the effects of eccentric and concentric training suggest it is unlikely to be solely mechanical stress or metabolic fluxes in the muscle.
A total of 117 Japanese subjects (62 men and 55 women) volunteered for the study. Subcutaneous adipose tissue (AT) and muscle thicknesses were measured by B-mode ultrasonography at nine sites of the body. Body density (BD) was determined the hydrodensitometry. Reproducibility of thickness measurements by ultrasonography was high (r = 0.96–0.99). Correlations between AT thickness and BD ranged from −0.46 (gastrocnemius) to −0.87 (abdomen) for males and −0.46 (gastrocnemius) to −0.84 (abdomen) for females. A higher negative correlation (r = −0.89) was observed for the sum of AT thicknesses (forearm, biceps, triceps, abdomen, subscapula, quadriceps, hamstrings, gastrocnemius, and tibialis anterior) both in males and in females. Slightly lower coefficients were observed between muscle thickness and LBM (r = 0.36 to r = 0.70 for males and r = 0.44 to r = 0.55 for females). Prediction equations for BD and LBM from AT and muscle thickness were obtained by multiple regression analysis. Cross-validation on a separate sample (33 men and 44 women) showed an accurate prediction for BD. The present findings suggest that B-mode ultrasonography can be applied in clinical assessment and field surveys. © 1994 Wiley-Liss, Inc.
The effects of a 1 year training period on 13 elite weight-lifters were investigated by periodical tests of electromyographic, muscle fibre and force production characteristics. A statistically non-significant increase of 3.5% in maximal isometric strength of the leg extensors, from 48411104 to 50101012 N, occured over the year. Individual changes in the high force portions of the force-velocity curve correlated (p<0.05–0.01) with changes in weight-lifting performance. Training months 5–8 were characterized by the lowest average training intensity (77.1+2.0%), and this resulted in a significant (p<0.05) decrease in maximal neural activation (IEMG) of the muscles, while the last four month period, with only a slightly higher average training intensity (79.13.0%), led to a significant (p<0.01) increase in maximum IEMG. Individual increases in training intensity between these two training periods correlated with individual increases both in muscular strength (p<0.05) and in the weight lifted in the clean & jerk (p<0.05). A non-significant increase of 3.9% in total mean muscle fibre area occurred over the year. The present findings demonstrate the limited potential for strength development in elite strength athletes, and suggest that the magnitudes and time courses of neural and hypertrophic adaptations in the neuromuscular system during their training may differ from those reported for previously untrained subjects. The findings additionally indicate the importance of training intensity for modifying training responses in elite strength athletes.
The purpose of this study is to analyze the effect of high-resistance (HR) and high-velocity (HV) training on the different phases of 100-m sprint performance. Two training groups (HR and HV) were compared with two control groups (RUN and PAS). The HR (N = 22) and HV group (N = 21) trained 3 d.wk-1 for 9 wk: two strength training sessions (HR or HV) and one running session. There was a run control group (RUN, N = 12) that also participated in the running sessions (1 d.wk-1) and a passive control group (PAS, N = 11). Running speed over a 100-m sprint was recorded every 2 m. By means of a principal component analysis on all speed variables, three phases were distinguished: initial acceleration (0-10 m), building-up running speed to a maximum (10-36 m), and maintaining maximum speed in the second part of the run (36-100 m). HV training resulted in improved initial acceleration (P < 0.05 compared with RUN, PAS, and HR), a higher maximum speed (P < 0.05 compared with PAS), and a decreased speed endurance (P < 0.05 compared to RUN and PAS). The HV group improved significantly in total 100 m time (P < 0.05 compared with the RUN and PAS groups). The HR program resulted in an improved initial acceleration phase (P < 0.05 compared with PAS).