Rate-Pressure Product Responses to Static Contractions Performed at Various Altitudes

Area of Science:

• Cardiovascular Physiology
• Altitude Medicine
• Exercise Science

Background:

• Adventure tourism increases altitude exposure, including for individuals with subclinical cardiometabolic disorders.
• Static exercise at altitude can exacerbate hemodynamic challenges, potentially increasing cardiac event risk.
• Understanding the cardiovascular response to static contractions at altitude is critical for public safety.

Purpose of the Study:

• To examine the cardiovascular response to, and recovery from, static handgrip exercise at varying altitudes.
• To assess the impact of altitude on heart rate, maximal voluntary contraction (MVC), and rate-pressure product during and after static exercise.
• To investigate the influence of altitude on the muscle metaboreflex during recovery from static exercise.

Main Methods:

• Eighteen participants completed static handgrip contractions (30% MVC) for 2 minutes at sea level, 1,500m, and 3,000m in Nepal.
• Cardiovascular responses were monitored during exercise and two recovery conditions: passive rest and ischemic challenge.
• Oxygen saturation, heart rate, MVC, and rate-pressure product were measured at each altitude.

Main Results:

• Oxygen saturation decreased with increasing altitude (-2% at 1,500m, -8% at 3,000m).
• Heart rate was significantly increased (~15%) at 3,000m during rest, exercise, and recovery, but not at 1,500m.
• Rate-pressure product was significantly elevated (~10%) during and after static exercise at 3,000m, indicating increased cardiac workload.

Conclusions:

• Static exercise at 3,000m significantly increases cardiac workload, as evidenced by elevated rate-pressure product.
• The muscle metaboreflex magnitude was not affected by altitude.
• Individuals with cardiac risks should exercise caution with static contractions at altitude, as this adds to the stress of dynamic activities.