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Measuring Energy Efficiency of MRS and SRS ascents
John Ball
Professor of Forestry, Extension Forestry Specialist
South Dakota State University.
ISA Board Certified Master Arborists and SAF Certified Forester
Tim Walsh
Vice President- Safety and Training
The Townsend Company, LLC.
Climbing techniques have evolved over the past century. Today, we have choices among moving rope systems (MRS) and stationary rope systems (SRS). The question often posed is: What is the most efficient?
We measured the heart rate and oxygen consumption of climbers ascending a line using several different MRS and SRS methods. The heart rate more than doubled from resting during the ascent to 40 feet, regardless of whether using MRS or SRS. Heart rate increased during climbing, in part, due to arm positioning. The heart must work faster to move blood against gravity when the arms reach up above the shoulders and pull.
Keeping the arms below the shoulders and using them more for balance than pulling maintains a lower heart rate during a climb. Stationary rope systems, which use leg muscles more than MRS resulted in the lowest heart rates, in the 100s and 110s, while the body thrust MRS method had climber heart rates reach into 160s bpm by the top of the ascent.
The VO2 rate, measured in the volume of oxygen consumed by the climber, also increased during ascents. Oxygen consumption increases five to ten times higher during the ascent than at rest. Climbers using SRS had the lowest average VO2 during the ascent.
Aerobic fitness is key for climbers. The oxygen demands of climbing require good lung capacity to consume oxygen and a strong heart to move the oxygenated blood. Cardio-respiratory exercises such as cycling or running are appropriate training for climbers. Strength training is also essential, both for the upper and lower body.
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