Acceleration forces at eye level experienced with rotation on the horizontal bar.

Area of Science:

• Sports Medicine
• Biomechanics
• Human Factors Engineering

Background:

• Negative G-force (-Gz) exposure can cause preretinal hemorrhage and headache.
• These symptoms are observed in activities involving headward force, such as gymnastics and trapeze arts.

Purpose of the Study:

• To measure and analyze the negative G-force (-Gz) experienced by gymnasts during a single-knee backswing on a horizontal bar.
• To compare the -Gz exposure and tolerance between child and adult gymnasts.

Main Methods:

• Lightweight accelerometers were used to measure -Gz at eye level.
• Key parameters calculated included rate of onset, peak -Gz, duration, area under the curve (G·s), and mean force.
• Data were compared against established -Gz tolerance curves.

Main Results:

• No significant differences were found in measured -Gz parameters between child and adult gymnasts.
• The best gymnast and child could exceed established -Gz tolerance limits within seconds.
• Elite gymnasts may experience forces that would induce symptoms in 6-25 seconds on a centrifuge.

Conclusions:

• Gymnastic maneuvers, like the single-knee backswing, generate significant negative G-force (-Gz) that can approach or exceed human tolerance limits.
• Both child and adult gymnasts, as well as participants in activities like monkey-bar climbing, are at risk of exceeding these physiological limits.
• Further research into protective measures and training adaptations may be warranted for athletes in high-Gz environments.