Is MuscleSound Simply Measuring Hydration?

MuscleSound is not measuring hydration: Here’s why

Research has shown that about 3 molecules of water are attached to every 1 molecule of  stored muscle glycogen. ^1,2 However these water molecules are very strongly bound to their glycogen ‘partner’ and - even when the body is in a dehydrated state - they will stay attached until the glycogen is broken down for energy. Only when this happens is the bound water released and made available to the rest of the body, in effect contributing to hydration status.³ Also, while dehydration does not impact normal muscle glycogen breakdown for energy, it does increase the rate of glycogen breakdown.⁴ Because of this, glycogen stores are used up much faster and the muscle becomes fatigued a lot sooner.

1. Neufer PD, Sawka MN, Young AJ, Quigley MD, Latzka WA, Levine L (1991) Hypohydration does not impair skeletal muscle glycogen resynthesis after exercise. J Appl Physiol (1985) 70:1490–1494
2. Olsson KE, Saltin B (1970) Variation in total body water with muscle glycogen changes in man. Acta Physiol Scand 80:11–18
3. Valentín E. et al. Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. Eur J Appl Physiol (2015) 115:1919–1926
4. Febbraio MA, Snow RJ, Stathis CG, Hargreaves M, Carey MF (1994) Effect of heat stress on muscle energy metabolism during exercise. J Appl Physiol 77:2827–2831.