We have probably all experienced at some time sore muscles and a loss of muscle function in the day/s following a hike. These symptoms are a result of damage to the muscle fibres caused mainly by eccentric contractions where the muscle lengthens while trying to contract to resist the force of gravity. Hiking has a lot of eccentric contractions, with damage most severe from hiking downhill due to the higher mechanical stress on the muscles. The load you are carrying, gradient, pace, distance and most importantly how well your muscles have adapted from previous hikes will all influence the severity of muscle damage and the recovery time. While there are a number of interventions that may help to reduce the negative effects and aid in recovery, nutrition plays a critical role.
Nutrition, specifically protein ingested as soon as possible after finishing your hike plays a critical role in improving recovery and helping to reduce the negative impact of sore muscles and muscle function loss on daily activities and exercise training.
To maximally stimulate muscle protein synthesis ingesting ~25-30g of protein as soon as possible after exercise is recommended. Two possible choices that are both convenient and non-perishable to have in your car when you finish your day hike, are trim milk powder (75 g serve) or a standard serve (~28 g) of WPI protein powder. Both deliver ~25 g of protein and when mixed with around 500 ml of water are great drinks to help with rehydrating. The milk powder provides 1140 kJ of energy, carbohydrates, calcium, and potassium. WPI powder provides 443 kJ of energy (a lot less energy than milk powder if you are trying to manage your weight) and a very small amount of carbohydrate (1 g). Cost-wise per serve, the milk powder is less than half that of the protein powder, while the protein powder is less weight per gram of protein, an important consideration if you are doing a multiday hike.