This study examined whether a short, high-intensity isometric exercise can influence physical performance and muscle characteristics several hours after it is performed. Specifically, the study compared the effects of a maximal isometric conditioning activity with a typical volleyball-specific warm-up routine. Highly trained male volleyball players participated in the study. Each participant completed two experimental conditions in a randomized crossover design: (1) a maximal isometric conditioning activity and (2) a volleyball-specific warm-up used as a control condition. The researchers evaluated changes in countermovement jump performance, muscle viscoelastic properties of the rectus femoris, and skin surface temperature over the quadriceps muscle. Measurements were taken before the intervention and again 6 hours and 30 hours later to determine whether the conditioning activity produced delayed improvements in neuromuscular performance. Understanding these delayed effects may help coaches and athletes optimize training and competition preparation strategies. The results of this study may provide insights into whether specific conditioning exercises can enhance or maintain explosive performance in volleyball players several hours after they are performed.
This study investigated the delayed effects of a maximal isometric conditioning activity on neuromuscular performance and muscle mechanical properties in highly trained male volleyball players. Conditioning activities are often used in sport to induce post-activation performance enhancement (PAPE), which may improve explosive performance such as jumping. While most studies have examined the acute effects occurring within minutes after the conditioning activity, less is known about possible delayed responses occurring several hours later. The aim of this study was to determine whether a maximal isometric conditioning protocol could influence countermovement jump performance, muscle viscoelastic properties, and skin surface temperature several hours after its application. The study also compared these effects with those produced by a volleyball-specific warm-up routine commonly used in training and competition settings. A randomized crossover design was used. Participants completed two experimental conditions on separate occasions: (1) a maximal isometric conditioning activity and (2) a volleyball-specific warm-up serving as a control condition. All participants were highly trained male volleyball players with experience in resistance and plyometric training. Neuromuscular performance was assessed using countermovement jump tests. In addition, muscle mechanical properties of the rectus femoris were evaluated using a myotonometric device to determine muscle stiffness and other viscoelastic characteristics. Skin surface temperature over the quadriceps muscle group was also measured to monitor potential physiological responses to the conditioning activity. Measurements were collected at baseline before the intervention and repeated 6 hours and 30 hours after the conditioning protocol or the control warm-up. This design allowed the researchers to examine whether a single high-intensity isometric stimulus could induce delayed changes in neuromuscular performance or muscle properties. Understanding delayed performance responses to conditioning activities may help coaches and athletes better plan training sessions and competition preparation. If such activities can produce beneficial effects several hours later, they could be strategically implemented earlier in the day to optimize performance during later training sessions or competitions.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
14
Participants performed a maximal voluntary isometric back-squat protocol consisting of 3 sets of 5 repetitions of 3-second maximal contractions at a knee joint angle of 120°. Each set was separated by 3 minutes of rest. The protocol was performed on a fixed barbell setup designed to allow maximal isometric force production.
Participants performed a 9-minute volleyball-specific warm-up consisting of mobility exercises and plyometric drills designed to prepare athletes for explosive movements typical for volleyball.
Academy of Physical Education in Katowice
Katowice, Silesian Voivodeship, Poland
Countermovement Jump Height (cm)
Vertical jump height measured during a countermovement jump using a dual force plate system (ForceDecks, VALD Performance) sampling at 1000 Hz. Participants perform maximal countermovement jumps with hands on hips. Jump height is calculated from center-of-mass velocity at take-off using the impulse-momentum method. Jump height will be reported in centimeters (cm).
Time frame: Baseline, 6 and 30 hours post-intervention
Quadriceps Skin Surface Temperature (°C)
Skin surface temperature of the quadriceps measured using infrared thermography (FLIR E54, FLIR Systems, USA). Thermal images are collected under standardized environmental conditions, and the region of interest is defined over the rectus femoris muscle. Temperature values will be reported in degrees Celsius (°C).
Time frame: Baseline, 6 and 30 hours post-intervention
Rectus Femoris Muscle Stiffness (N/m)
Muscle stiffness of the rectus femoris measured using a handheld digital myotonometer (MyotonPRO, Myoton AS, Tallinn, Estonia). The device applies a brief mechanical impulse (0.4 N for 15 ms) to the muscle and records the resulting oscillations of the tissue. Stiffness values are calculated from the oscillation response as an indicator of the muscle's resistance to external deformation. Measurements are performed at the midpoint of the rectus femoris with the participant in a relaxed supine position. For each measurement site, the mean value of five consecutive impulses is used for analysis. Muscle stiffness will be reported in Newtons per meter (N/m).
Time frame: Baseline, 6 hours post-intervention, 30 hours post-intervention
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