發表論文全文：
The Effect of Different Sequences of Aerobic and Resistance Exercises on
Electromyography during Maximal Voluntary Isometric Contraction of Quadriceps.
Yu-Han Wang1, Hsien-Te Peng1 and Chen-Yi Song2
Department of Physical Education of Chinese Culture University, Taipei, Taiwan1;
School and Graduate Institute of Physical Therapy, College of Medicine, National
Taiwan University, Taipei, Taiwan 2
BACKGROUND: Combining strength and cardiovascular training is popular in
physical fitness training and athletic training programs. AIM: To investigate the effect
of different sequences of aerobic and resistance exercises on electromyography (EMG)
during maximal voluntary isometric contraction of quadriceps. METHODS: By
counter-balanced design, 9 recreationally active males completed two sequences of
tests: a) aerobic + resistance exercises (AR) and b) resistance + aerobic exercises
(RA). The aerobic exercise is 65% VO2max running for 30 minutes. The resistance
exercises are 3 sets of 4 resistance exercises including12 repetitions of bench press,
leg extension, front lat pull down and leg curl at 60% 1RM each with a 2-min rest
between sets and exercises. The EMG of maximal voluntary isometric contraction of
quadriceps including rectus femoris (RF), vastus lateralis (VL) and vastus medialis
(VM) were measured before and after exercises (pre- and post-test), A repeated
measured two-way ANOVA was used to examine the differences between sequences
and pre- and post-test. RESULTS: The RA post-tests were significantly lower than
pre-tests on EMG of the VL and VM (both p<.05).The AR post-tests were
significantly lower than pre-tests on EMG of the VL. The voluntary activation change
of VL and RF after RA was significant larger than after AR.CONCLUSION:
Performing treadmill exercise before resistance exercise appears to improve the
quality of exercise compared with performing treadmill exercise at the end of the
exercise sequence.
Key Words: muscle activation, aerobic exercise, resistance exercise
Introduction
The combination of aerobic and resistance exercise is common in physical training (1).
Aerobic exercise can enhance cardiovascular system, and resistance exercise can
develop strength and hypertrophy. Although the fundamental and biological theories
of aerobic and resistance are different, the use of combining aerobic and resistance
exercise for athletic programs is necessary and would get both cardiovascular and
muscular benefits (28). It is quite common to see recreational exercisers combine
exercise modalities into 1 exercise session, however, but research about the different
sequences of aerobic and resistance exercise on post-exercise acute effects is rare and
unclear.
Resistance exercise could enhance muscular strength, power, endurance and
hypertrophy. It had been documented that the during and post exercise acute
hormone and muscle local machine responses were very importance for muscle
adaption. The common response of post exercise acute response is muscle fatigue,
and it would induce strength decrease and change the recruitment of active muscle.
It had been shown that the different sequence of aerobic and resistance exercise would
‧
have higher physiological response on Vo2max, heart rate and RPE in resistance
exercise before aerobic exercise group than aerobic exercise before resistance exercise
group, and they concluded that resistance exercise appeared to make subsequent
aerobic exercise more difficult. The order in which resistance and aerobic exercise
are sequenced may also affect the magnitude of exercise loads that may induce
different fatigue level of muscle after exercise.
Specifically, it is unknown if previous exercise influences the quality of the secondary
activity, so the effects of same exercise loads with different sequences of aerobic and
resistance exercise on muscular performance is our primary aim. Secondly, we
measure the exercise volumes of different sequence of aerobic and resistance exercise.
So we investigate the effect of different sequences of aerobic and resistance exercises
on electromyography (EMG) during maximal voluntary isometric contraction of
quadriceps.
Method
Seven physically active male college students (Table 1) participated in this study. All
subjects were currently physically active, which was defined as engaging in strength
training and jogging at least 2 days each per week for the past 6 months. All subjects
read and signed an informed consent form and completed a physical activity and
medical history questionnaire.
Table 1 Subject characteristics
subject
Height（cm） Weight(kg)
Age(y)
VO2max(ml/kg/min)
7
172.9 ± 1.3
23.9 ± 0.9
56.6 ± 1.7
68.4 ± 2.7
Equipments：
The treadmill (Trackmaster), resistance machines (Smith), metabolic analysis
(VMOax29, SensorMedics, Yorba Linda, California, USA) and electromyographic
(TeleMyo 2400T, Noraxon USA Inc., Scottsdale, AZ, USA) were used.
Preliminary Assessments：
Subjects participated in four testing sessions, during the first of which each subject’s
maximal aerobic power (MAP) was determined. The second session was to determine
the Maximal strength (1RM). The subsequent two testing sessions, in randomized
order, were composed of either (Resistance exercise＋Moderate intensity aerobic
exercise, RA) or (Moderate intensity aerobic exercise＋Resistance exercise, AR)
training protocols for which PRE and POST test.(Fig. 1)
Day 1
Day 2
MAP
Maximal strength (1RM)
Randomized
Day 3
PRE test
(RA)
POST test
Day 4
PRE test
(AR)
POST test
Fig.1 Experimental setup with PRE and POST tests
(1) Maximal aerobic power：Each subject completed a maximal graded exercise test
on the treadmill. Subjects walked at a self-selected pace at 15% grade for 3
minutes after which they jogged at a moderate intensity, self-selected pace for 3
more minutes. The grade was then increased by 1.5% every minute while speed
remained constant, continuing until the subject reached volitional fatigue. The
maximal graded exercise test was considered a valid test if 3 or more of the
following 4 criteria were met: (a) maximal HR within ± 15 b·min-1 of
age-predicted maximum HR or a HR that failed to increase with increased
workload, (b) respitory exchange ratio >1.10, (c) RPE greater than 17 (6–20 scale),
and (d) plateau of oxygen consumption (< 150 ml/min ) despite an increase in
workload （Riechman, Zoeller, Balasekaran, Goss, & Robertson, 2002）.
(2) Maximal strength： A 1-Repetition Maximum (1RM) was determined for each of
the 4 resistance exercises. A 1RM was defined as the maximum amount of weight
lifted during 1 full range of motion. The procedures used to determined 1RM are
described elsewhere （ Faigenbaum, Milliken, & Westcott, 2003; McBride,
Triplett-McBride, Davie, Abernethy, & Newton, 2003）。
(3) PRE and POST testing sessions：Each subject performed the two different training
protocols on separate occasions. Upon their arrival at the laboratory, subjects were
equipped with the electrodes necessary for recording electromyographic (EMG)
activity. The PRE and POST testing were asked subjects to perform three MVCs
of the knee extensor muscles with maximal rate of torque development, with ≈ 30
s rest between each. An EMG system was used to record electrical activity of the
vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) during
voluntary contractions. Silver chloride surface electrodes (3M ™ Red Dot ™ wet
gel electrode) with preamplifiers were placed in a bipolar configuration with a 1.8
cm inter-electrode distance, in line with the muscle’s fiber orientation. Low
resistance between the two electrodes (<5 k Ω) was obtained by abrading the skin
with emery paper and cleaning with alcohol-ether-acetone mix. A reference
electrode was attached to a body area remote from the studied muscles. The EMG
signals were pre-amplified with a gain of 1000, with a common mode-rejection
ratio of 110 dB and filtered (4th -order Butterworth filter) with a pass-band of
5–500 Hz.
(4) Training sessions：The testing sessions, in randomized order, were composed of
either Resistance exercise＋Moderate intensity aerobic exercise, RA or Moderate
intensity aerobic exercise ＋ Resistance exercise, AR. Resistance exercise
including 4 exercise which were bench press, leg extension, front lat pulldown and
leg curl. 70% of the 1RM was used for the exercises during the resistance exercise
phase, each exercise were 12 repetition. 90s rest were allowed between exercises.
Moderate intensity aerobic exercise subjects performed one 30 min session of
running on the treadmill. During the 30 min session of aerobic training each
participant ran at 65 % V‧O2max of their MAP for the duration of the training
session.
Statistical analysis
Standard statistical methods were used for the calculation of the means and standard
deviations (SD). Statistical comparison the rmsEMG of PRE test with POSTtest was
performed by student’s paired t -test. Prepare the change of VL, VMO and RF (%). A
level of p < 0.05 was used to identify statistical significance.
Result
The raw RMS values of VL,VMO and RF muscles associated to the MVC of the knee
extensors significantly decreased after the Resistance exercise＋Moderate intensity
aerobic exercise, RA. (Table 2) The raw RMS of VL (POST：6.11±2.57，PRE：
9.3±3.56 μV, p<.05).The raw RMS of VMO (POST：4.37±2.27，PRE：6.93±2.76 μV,
p<.05). The raw RMS of the RF (POST：4.37±2.27，PRE：6.93±2.76 μV, p<.05). The
raw RMS values of RF muscles associated to the MVC of the knee extensors
significantly decreased after the Moderate intensity aerobic exercise＋Resistance
exercise, AR. (Table 2) The raw RMS of the RF (POST：5.52±1.75，PRE：7.04±2.35
μV, p < 0.05)
Table 2 Raw RMS values of VL, VMO and RF muscles
RA
AR
PRE
POST
PRE
POST
VL(μV)
9.3±3.56*
6.11±2.57
9.46±3.40 *
8.90 ±2.93
VMO(μV)
6.93±2.76 *
4.37±2.27
7.09±2.50
5.33±1.57
RF(μV)
7.04±2.35*
5.52±1.75
5.92±1.44
5.92±1.78
*Indicate that POST values were significantly lower than PRE values respectively at p
< 0.05
The voluntary activation change of VL after RA was significant larger than after AR.
(RA : 34.85% ; AR : 12.56%, p<.05) (Fig. 2) . The voluntary activation change of the
RF after RA was significant larger than after AR. (RA : 25.42% ; AR : 1.51%, p<.05)
(Fig. 3) .
Fig.2 activation change of VL
change of the RMS %
VL
40
30
20
VL
10
0
RA
AR
Fig.2 activation change of VL
change of the RMS %
RF
30
20
RF
10
0
RA
AR
Conclusion
The purpose of this study was to analyse the amplitude and change of the voluntary
activation induced by a training session combining an aerobic and a resistance
component. The key findings were that decreases in rawRMS of the knee extensor
muscles following a single combined training session: (1) in Resistance exercise＋
Moderate intensity aerobic exercise, RA, the VL,VMO and RF voluntary activation
are significant lower in POST test. (2) in Moderate intensity aerobic exercise＋
Resistance exercise, AR, only the VL voluntary activation is significant lower in
POST test. (3) The VL and RF of voluntary activation reduced in RA than AR.
According to the different definitions of fatigue (Enoka and Duchateau, 2008) , a
decrease in torque developed by the knee extensor muscles during isometric MVC
after the CTP and ATP confirms the presence of fatigue. The ~ 9 % MVC torque
reduction observed after the CTP could not be easily compared with the literature
because no studies were done on the acute effect of this type of combined training.
Reductions in voluntary activation of the quadriceps muscles have been previously
highlighted after cycling exercise alone (Bentley, Smith, Davie and Zhou, 2000 ) and
after maximal concentric exercise (Babault, Desbrosses, Fabre, Michaut and
Pousson) , hence the occurrence of central fatigue after the CTP is not surprising.
These results indicate that a decreased descending command from supraspinal and / or
spinal centres was one of the causes of MVC loss, after the CTP and the ATP. The
techniques used in this study, did not allow us to determine if the central fatigue
originated from a site at a supraspinal or a spinal level (Gandevia, 2001) .
Performing treadmill exercise before resistance exercise appears to improve the
quality of exercise compared with performing treadmill exercise at the end of the
exercise sequence.