Hydration & running: okay to carry the can?

Good running form is critical for good running economy, enabling runners to cover more ground for less energy expended. In studies that have researched running, and what helps to promote good running form, most scientists have (quite naturally) focused on the role of running biomechanics, running shoe choice, strength and strength imbalances etc. However, what hasn’t been studied is the effect on form and running efficiency of items that runners might hold or carry such as water bottles held in the hand and bottle belt holders. Water is heavy stuff so carrying it around could have an impact on running form – particularly when carried in bottles held in the hand, which requires constant accelerating and decelerating movements. So what effect does carrying water have?

The research

To try and find an answer to this question, scientists from the University of Florida looked at the different kinematics (movement patterns), rates of energy use and heart/lung responses while running both with and without water bottles/bottle belt holders [Int J Sports Physiol Perform. 2018 Vol 13 (8) 977-985]. In the study published last month, 42 trained runners completed four runs on a carefully calibrated treadmill. Each run was performed under identical conditions except for what the runners wore during the trial:

• A full hand-held water bottle (16.9 fluid ounces weighing 454 grams).
• A half full hand-held water bottle (8.4 fluid ounces weighing 227 grams).
• A waist-worn bottle belt holder (hydration belt weighing 676 grams).
• A control run, where the runners held or carried nothing. Sophisticated gas analysis was used to determine how much energy the runners used per mile (running efficiency) and the movement patterns were determined using 3-dimensional video analysis. The results from the four trials were then compared to see what effect (if any) carrying water had on running efficiency.

Small differences

When the researchers analysed the movement patterns of the runners, they found small but significant differences. In particular, carrying the water bottle resulted in a slightly more flexed elbow on the carrying side. The runners also exhibited slightly more rotation in the pelvis region when carrying water devices. However, in terms of running efficiency, there was absolutely no difference in the amount of oxygen the runners consumed, or how efficiently they ran. The researchers concluded that ‘carrying of water by hand or on the waist does not significantly change kinematics of running motion, rates of oxygen use and energy expenditure over short durations’.

Implications for runners

On the face of it, these findings are somewhat surprising; you might expect that carrying a heavy object in one hand or wearing a heavy belt would impair running efficiency, even if only by a small amount. The most likely explanation as to why this didn’t happen is that the runners subconsciously made adjustments to their joint moments and powers, which helped to preserve balance and protect the runners’ lower extremity joints, while maintaining running efficiency. These findings are reassuring for runners who like to drink on the move. It’s worth cautioning however that runners carrying heavier loads and/or running for long durations might experience fatigue in the carrying arm, which could then be detrimental to running efficiency.

PRACTICAL SUGGESTIONS

• Start your longer runs fully hydrated, which will reduce the need to carry water. As a rule of thumb, your urine should be no darker than a pale straw colour.
• When carrying water, choose a water bottle with an ergonomically designed handle and that suits your hand size.
• Those with weaker grip strength should consider a bottle fitted with hand gloves or bungees, which helps remove the strain on the forearm muscles.
• When carrying larger amounts of water/fluid for very long runs in hot conditions, a hydration belt will be more comfortable. It also has the benefit that empty bottles can be replaced into the belt without the need to grasp them in the hand for the rest of the run.