By Kelson Geber, MTI Coach/Researcher
BLUF
Mountain Tactical Institute (MTI) conducted a two-month single-person mini-study to examine the impact of weight reduction on speed during fast alpine ascents. The study found that reducing pack weight in increments of 8 ounces (227 grams) consistently improved climbers’ speed and potentially decreased their exposure to hazards. Overall, the study concluded that lighter packs enhance climbing performance and safety, with an average speed increase of 2% per 8-ounce reduction in pack weight. This study specifically examined ‘the approach, the initial part of an alpine ascent where climbers cover horizontal or moderately inclined terrain. The findings do not extend to vertical terrain, where different muscle groups and technical skills are more critical.
Background
When it comes to fast alpine ascents, every ounce counts. At least, that’s the prevailing wisdom in the mountaineering community.
A quick search online reveals numerous articles and guides on how to pack light for alpine climbs. However, these lighter items often come at a higher cost and may be less durable. For climbers undertaking longer expeditions or those who face unpredictable weather, the trade-off between weight and durability becomes even more critical, as heavier gear might offer better protection and reliability.
This study aimed to answer critical questions: Is it worth leaving behind essential items like outer layers and first aid kits or severely limiting food and water to save a few pounds? Is investing in more expensive, lighter gear really justified?
We focused on climbers who prioritize speed and efficiency, often called “light and fast” alpine ascent enthusiasts. We aimed to determine how small reductions in pack weight impact speed during alpine ascents.
Study Design and Deployment
The study was conducted with a single participant to maintain consistency and control over the data, ensuring that variations in performance were due primarily to pack weight changes. However, this design also limits the generalizability of the findings, as individual responses to weight reduction can vary. The designated route covered 3.25 miles with a 2,000-foot vertical gain. This particular elevation gain allowed sufficient time under load, ensuring the participant could be adequately assessed under the conditions set for the study.
To ensure consistent effort levels across all trials, the participant’s heart rate was governed at Zone 3, a level chosen to reflect a balance between intensity and sustainability. Zone 3 typically represents a pace that can be maintained for extended periods, making it ideal for assessing endurance during alpine ascents. The maximum heart rate was determined through a five-minute max-effort run. This data set the Zone 3 heart rate maintained throughout each iteration.
The study began with a pack weight of 22 lbs, representing the heaviest load assessed carried during a summer fast alpine ascent. The lightest pack weight tested was 15 lbs. Over the course of the study, 16 iterations were conducted on the designated route, with the pack weight reduced by 8 ounces in each successive climb. Repetition 4 was repeated due to the influence of an abnormally hot day.
This structured approach allowed for precise measurement of incremental weight reductions’ impact on climbing speed and endurance, providing valuable insights for future research and practical application.
Lab Rat Details:
- Sex: Male
- Age: 39
- Height 6′
- Weight: 180′
- GPS Watch/ Heart Rate Monitor: Garmin Fenix 5 w/ Garmin HRM-Tri Chest Strap
- Max Heart: 185
- Zone 3 (75-80% Max HR): 138-148 BPM
- Current fitness level: This lab rat entered this study with a foundational level of aerobic fitness. Throughout the study, a deliberate effort was made to maintain this aerobic base by carefully limiting weekly mileage to no more than 15 miles of aerobic work, avoiding both excessive mileage and interval training.
Results and Discussion
Question 1: What is the influence of 8 ounces on time and speed?
Overall, the data suggests that each 8-ounce reduction in pack weight leads to a gradual improvement in speed, averaging around a 1.62% increase in speed over ground (SOG). The lighter the pack, the more significant the gains in speed, which can translate into more efficient and quicker ascents. The influence of weight reduction is consistent, although environmental factors like temperature showed the ability to influence results slightly.
Example:
For a 15-mile distance:
- With a 22 lb pack, it would take approximately 5 hours and 36 minutes.
- Time= Distance/SOG: 15miles/2.68 (SOG)= 5.60 hours ( 5 hours 36 minutes )
- With a 15 lb pack, it would take approximately 4 hours and 31 minutes.
- Time= Distance/SOG: 15miles/3.32 (SOG)= 4.52 hours ( 4 hours 31 minutes)
The difference is 1 hour and 5 minutes.
This graph estimates how much your speed over the ground could increase as your pack weight decreases.
Question 2: How the Results Can Influence Risk Decisions and Gear Selection
From what we know above, reducing pack weight increases speed over ground, ultimately getting you up and down the mountain quicker. How does this help?
- Reduced Exposure Time: Faster ascents meant less exposure to environmental hazards such as weather changes and unstable terrain.
- Improved Safety Margins: Lighter packs allowed quicker movements, enabling the climber to respond more effectively to unforeseen challenges.
- Greater Flexibility in Gear Choices: Knowing the benefits of reduced weight, climbers can prioritize selecting multi-functional, lightweight gear that maximizes utility while minimizing load, increasing both safety and performance.
What Else Could Account for Speed Increase?
Weather and Environmental Conditions:
- Temperature’s Role: Cool temperatures were found to improve speed by reducing the physiological burden of heat. This suggests that climbers might perform better in cooler environments or that they should start their ascents during cooler parts of the day. On 21-May-24 (42°F), cooler weather correlated with improved speed (3.01 mph), suggesting cooler weather may aid performance by reducing heat stress and fatigue. On 28-May-24, despite a pack weight reduction of 20.5 lbs, the upward movement time increased to 1:12:26, achieving a speed of 2.69 mph. This is inconsistent with the trend of reduced weight correlating with faster speeds. Speculation on this date could be due to the high temperature of 79°F, significantly higher than other days in the study. The increased heat likely caused more significant fatigue and slower performance, highlighting the impact of weather on speed.
- Overcast Conditions: Consistent overcast conditions could help maintain a steady pace by minimizing heat exposure and reducing the risk of dehydration, both of which can slow down ascents.
Other Contributing Factors:
- Fatigue Management: The gradual improvement in speed might also be partially attributed to the participant’s adaptation to the specific physical demands of the route over time. As the study progressed, the participant likely became more efficient in managing fatigue, contributing to faster ascents.
- Terrain Familiarity: Increased familiarity with the terrain could have contributed to the speed gains observed. As the participant repeated the route, their knowledge of the most efficient paths, pacing, and techniques likely improved, leading to quicker ascents.
- Fitness Improvement: It’s likely the single lab rat’s uphill climbing fitness improved – i.e. his aerobic base developed and increased. As his fitness improved, his overall speed increased at the same heart rate. His “slow” became faster. This may account for a significant part of the gradual and overall speed increase.
Next Steps: Refining the Study Design
Testing Steeper Terrain:
Engaging Different Muscle Groups: The next phase of this research should focus on testing similar weighted movements on steeper slopes (35-50 degrees), where different muscle groups are engaged. This would provide valuable insights into how weight reduction and aerobic conditioning impact performance under more challenging conditions, potentially revealing whether the observed trends in speed improvement hold true on steeper terrain.
Controlled Aerobic Base Development:
Repetition with Aerobic Conditioning: Repeating the study with a more structured aerobic base development program would allow for a clearer understanding of how aerobic improvements contribute to speed. By controlling for aerobic gains, the study could more accurately isolate the effects of weight reduction on speed.
Standardized Testing Conditions: Future studies should also aim to standardize testing conditions, such as ensuring consistent weather and time of day, to minimize external variables that could influence results.
Larger Weight Reductions:
Reducing Repetition Requirements: Larger increments in weight reduction could expedite data collection by reducing the number of repetitions needed. This approach might also limit potential aerobic gains during the study, which could otherwise skew results. Despite conducting the test in the early morning when body weight is most stable, natural fluctuations of 1-5 pounds due to water retention, food intake, glycogen storage, and bowel movements could still impact outcomes. Using larger weight reduction (e.g., 1-2 pounds) increments would help mitigate these variables, streamlining the data collection process while maintaining the study’s focus on the relationship between pack weight and speed.
Additional Relevant Studies