Rest-interval length affects leukocyte levels during heavy resistance exercise

Area of Science:

• Exercise Physiology
• Immunology
• Sports Science

Background:

• Resistance exercise elicits significant physiological responses, including alterations in immune cell populations.
• The impact of varying rest intervals on these immune responses during heavy resistance exercise remains incompletely understood.

Purpose of the Study:

• To investigate the influence of different rest interval durations (1-minute vs. 3-minute) on leukocyte levels following heavy resistance exercise.
• To examine the relationship between immune cell responses and markers of muscle damage.

Main Methods:

• Nine college-aged men performed a leg press protocol (10 sets of 10 repetitions at 65% 1RM) with either 1-minute or 3-minute rest intervals.
• Blood samples were collected at rest, immediately post-exercise, and 1.5 hours post-exercise to analyze leukocyte counts.
• Serum creatine kinase (CK) activity was measured 24 hours post-exercise.

Main Results:

• A significantly greater increase in lymphocytosis (83% vs. 16%) and monocytosis (47% vs. 15%) was observed immediately post-exercise following the 1-minute rest interval compared to the 3-minute interval.
• Serum CK activity was elevated to a greater extent 24 hours post-exercise after the 1-minute rest protocol.
• A positive correlation was found between the immediate post-exercise lymphocytosis and serum CK levels.

Conclusions:

• Shorter rest intervals (1 minute) during heavy resistance exercise, with constant total work, lead to a more pronounced lymphocytosis and monocytosis.
• These findings suggest that manipulating rest periods can modulate the acute immune response to resistance training.