Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT02717793 |
| Other study ID # |
SERC231013 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
Phase 1
|
| First received |
February 6, 2016 |
| Last updated |
March 25, 2016 |
| Start date |
October 2013 |
Study information
| Verified date |
March 2016 |
| Source |
Universiti Tunku Abdul Rahman |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
Malaysia: Universiti Tunku Abdul Rahman |
| Study type |
Interventional
|
Clinical Trial Summary
1 repetition maximum (RM) and Maximum Voluntary Contraction (MVC) with digital dynamometer
are popular method of measuring muscle strength. The types of muscle contraction involved in
both are different, 1RM involves isotonic muscle contraction (ITMC) and MVC with digital
dynamometer involves isometric muscle contraction (IMMC). There are several risks involved
in measurement of 1RM, such as delayed onset muscle soreness (DOMS) and unsafe for
pathological joints etc, this can be reduced if IMMC is used in measuring strength. Though
both cannot be equated as they are different type of contraction, therefore the purpose of
this study was to compare between 1RM measurement and isometric MVC using a digital
hand-held dynamometer in healthy females. Twenty nine young females (mean age = 20.77 ±
1.28) without any weight training experience (mean BMI = 20.43 ± 1.85) volunteered for the
study. It was a crossover trial where 48 hours of rest period was given between each
measurement technique. The result showed moderate correlations (r = 0.365-0.847) between 1RM
and MVC. A simple linear regression analysis revealed a significant estimated regression
equation for dominant and non-dominant hands. [Dominant, Y=0.391x + 1.472; Non-Dominant,
Y=0.251x + 2.629; (Y: 1RM, x: Isometric)] with low standard error of estimation value of
(Dominant, 0.74; Non-dominant, 0.80). The result also showed no significant difference
between these derived equations and Brzycki 1RM prediction equation. Therefore, it was
concluded that both prediction equations can be used interchangeably to predict the strength
of a person, and thus IMMC can be used to predict 1RM in healthy females.
Description:
A dynamic isotonic muscle contraction (ITMC) causes joint movement and excursion of a body
segment as the muscle contracts and shortens or lengthens under tension. One repetition
maximum (RM) is defined as the maximum weight a person can lift only once in a complete
range of motion. It is a gold standard for measuring muscular strength therefore it is used
for most of the strength training programmes. The 1RM test has been shown to be reliable in
various populations. Further, setting an intensity of resistance training based on a
percentage of the 1RM has been found to be effective for improving outcomes such as muscle
strength, muscle power, and muscle hypertrophy. Many studies have shown increase in strength
when RM testing is repeated over several days to weeks. Therefore, most testing protocols
suggest that strength should be measured more than once; typically 2 or 3 testing sessions
is recommended.
A familiarisation process prior to 1RM strength testing is necessary to ensure a reliable
test result, this minimizes learning effect or systemic bias. It has been shown that without
a familiarisation process prior to strength testing, there is a significant increase in the
expression of muscle strength. In many studies, investigators have suggested that older
individuals need 8—9 sessions of 1RM testing in order to increase the consistency of the 1RM
measurements. Therefore, multiple familiarization sessions are beneficial for RM
measurements. This draws us to a thought that such sessions may not be practical for studies
examining training outcome to record the strength changes for several different resistance
exercises as well as numerous other functional parameters. This unnecessarily increases the
time requirement and extends the duration of the study, both of which might increase the
likelihood of participant dropout in studies and loss of interest in exercise for clients.
In the measure of 1RM, especially in patients, using a heavy weight and large number of
repetitions imposes a greater risk of injury.
Having been said that, 1RM measurement requires a long period of testing to have a
consistent value; it also requires familiarization technique which is also very intense and
extensive procedure. To avoid the risk, related to the measurement of 1RM, many studies have
been conducted to produce regression equations for predicting 1RM strength. There are other
studies too that have been undertaken to determine the accuracy of such equations.
Prediction of 1RM strength allows an exercise specialist to assess an individual's maximal
lifting capacity without subjecting the novice lifter to the increased risk associated with
a 1RM lift. The advantage of calculating 1RM using the formula is that, it provides the
therapist with the most widely accepted measure of strength without the risks associated
with the formal 1RM testing. However the 1RM load lifting also requires great concentration
and considerable mental preparation for the subject which can be an extremely intense
experience that leaves them unsure and scared. Although there is no real data concerning the
risk of injury in this test, the potential risk may be significantly increased by using very
heavy loads.
Testing 1RM uses isotonic movement which may be associated with increased risk of injury as
it may include high speed of movement, inability to spread workload evenly over the entire
ROM, unsafe for pathological joints, delayed onset of muscle soreness, requirement of
equipment which can be expensive, and increased risk of injury, if the movement is done
incorrectly. Measuring of 1 RM using the traditional way and by using prediction equation,
both involve risk, therefore it brings us to an idea of the use of isometric type of
movement in predicting 1RM.
Isometric contraction is a static form of exercise in which a muscle contracts and produces
force without an appreciable change in the length of the muscle and without visible joint
motion. It is a very popular method of testing the isometric strength of a particular
muscle. It is a very easy, fast and accurate method of testing strength of a muscle.
Isometric measurement by Lafayette Manual Muscle Test System (model 01163) has been proven
to be highly reliable with in inter-class coefficient of 0.85. This method eliminates most
of the risk factors that is observed in measuring 1 RM using the traditional way and the
prediction equation. Furthermore, it is cost effective, more convenient to be done, and it
does not aggravate sensitive joint surfaces. Therefore it reduces most of the risk involved
in measuring 1RM using the traditional way and by using prediction equation. However, it is
worth mentioning that, isometric strength measurement cannot be replaced with the 1RM
measurement which is a dynamic method.
Blazevich et al in their study of reliability and validity of two isometric squat (IS)
tests, reported that IS with an isometric rack showed significant and high correlation (r =
0.77) with 1RM squat. However, when Demura, S studied the relationship between 1RM and
isometric measurement of squat(IS), their study showed that some component (wide stance and
parallel depth) of the squat correlated well with 1 RM whereas others did not. Simple linear
regression analysis in their study revealed a relationship of Y = 0.992X + 30.3 (Y: 1RM, X:
IS). This suggested that the IS using a back dynamometer may become an effective index for
predicting 1RM squat. However, since the standard error of an estimate provided by the
regression equation was quite large, (11.19 kg) therefore, it could not estimate 1RM in
non-athletes; this study concluded that estimating a 1RM by Isometric squat using a back
dynamometer maybe difficult. Though some studies have been conducted to estimate 1RM from
isometric strength measurement, there is a dearth in literature to prove the same. Therefore
the investigators aim to find out if isometric strength can be compared with 1RM in female
subjects without weight training experience. Hence the purpose of this study is to find if
there can be comparisons between 1RM (Brzycki's prediction equation) measurement and
isometric MVC using a digital hand-held dynamometer in healthy females.
