Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT06464120 |
| Other study ID # |
2024Y002 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
January 2, 2024 |
| Est. completion date |
February 28, 2024 |
Study information
| Verified date |
June 2024 |
| Source |
Universiti Putra Malaysia |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
With the advancement of sports science, Post-Activation Potentiation (PAP) has become a focal
point of research, garnering significant attention for its underlying physiological
mechanisms. Current studies suggest three primary mechanisms: 1) phosphorylation of myosin
regulatory light chains (RLCs); 2) increased recruitment of high-threshold motor units; and
3) a reduction in sarcomere length heterogeneity within muscle fibers due to pre-stimulation
(Liu & Li, 2017). These mechanisms collectively contribute to an effect known as
Post-Activation Performance Enhancement (PAPE), which significantly enhances muscle strength
and explosiveness shortly after activation (Blazevich & Babault, 2019).
During the activation process of motor units with increasing loads, low-threshold motor units
are recruited first, followed by high-threshold motor units. As the load increases, the root
mean square (RMS) value increases linearly, further promoting the overlap of motor unit
potentials and the rise in RMS values. This overlap in activation timing among adjacent motor
units results in greater overall muscle force output (Liu, 2008; Tian, 2009). The
significance of this lies in the fact that as the degree of muscle activation increases,
especially under incremental loads, the muscle's ability to adapt to subsequent strength or
explosive tasks may be enhanced.
In competitive sports, optimizing the relationship between warm-up and performance is
crucial. Research indicates that the duration of PAPE varies with individual differences,
training type, intensity, and recovery intervals. The characteristics of the PAPE effect also
differ. Additionally, following constant loads, the enhancement and decay rates of
performance in PAPE show varying rates at different times, and these rates do not exhibit a
symmetrical linear change in absolute value (Liang, M 2020; Guo, W et al. 2018; Liu, R and
Li, Q. 2017). The competition pace in sports demands precise modulation of performance
enhancement rates after activation, and athletes can leverage these characteristics by
selecting appropriate loading forms to trigger PAPE at critical moments in competition. To
explore the enhancement or decay rates of performance over different time domains, our
research team designed a protocol consisting of incremental loads.
Description:
First, participants underwent a squat 1-RM test using the NSCA testing protocol. The
induction exercise was barbell-loaded squats. In the constant load group, the stimulation
intensity was set at 90% of the 1-RM, with one set of four repetitions of barbell half-squat
jumps . In the incremental load group, the stimulation intensities were set at 5RM, 4RM, 3RM,
and 2RM, with one set of one repetition of barbell half-squat jumps for each load intensity.
Both the 1-RM test and squat induction exercises were conducted using a Smith machine, and
protective personnel were present on both sides. The testing movement involved static
half-squat jumps that aimed to enhance the stability of the test and reduce interference from
arm swinging. The static half-squat jump required participants to stand with their feet
shoulder-width apart on the force plate, hands on hips, and knees flexed to a semi-movement
range, and they had to maintain the position for one to two seconds. Following this,
participants exerted maximal effort to jump upward (with no visually noticeable downward
squatting during takeoff) before naturally descending and maintaining the position for
another one to two seconds. Throughout the entire process, both feet were to remain within
the force plate area.
Experimental procedure The participants began with a 10-minute slow jog and dynamic
lower-limb stretches. As a baseline, the participants' dynamic data for unloaded static
half-squat jumps were collected after a 5-minute rest. Following another 5-minute rest, the
constant load group underwent one set of four half-squat jump inductions at an intensity of
90% 1-RM. The incremental load group underwent inductions at each load intensity, with one
set of barbell half-squat jump exercises for each intensity. The participants received verbal
cues and encouragement for each repetition. Dynamic data for static half-squat jumps were
collected at 15 seconds, 3 minutes, 6 minutes, 9 minutes, and 12 minutes after the end of
each exercise session. At each time point, two valid repetitions were collected, with verbal
cues and encouragement provided to the participants for each repetition. Each set of two
half-squat jumps did not exceed 10 seconds. The interval between static half-squat jump
testing and 1-RM testing was greater than 48 hours .
