Protocols used to determine the influence of backpack load on physiological variables. Systematic review

Professional mountain rescue mountain groups use backpack equipment in their professional activities. The velocity of ambulation, gradient, load and the participant's physical characteristics have been described in the scientific literature as influential factors on response to exercise. The purpose of the present systematic review is to assess the protocols used to investigate the effects of backpacks and their influence on physiological responses at laboratory. A total of 14 articles were included in the review. Most research studies indicated participants were not experienced with backpack carriage. We observed a certain threshold on physiological changes in response to exercise was between 20 and 40 kg of backpack load. In conclusion, there is a heterogeneity of protocols used at the laboratory, hampering the comparison between different results. Future research should focus on the design of protocols that reproduce real scenarios of targeted populations. Rescue groups, firefighters and military personnel carry load with backpack in emergency interventions. This review analyzes different types of methodological protocols that investigate the influence of backpack load on physiological responses during exercise. The result will help manufacturer design backpacks considering the physiological burden of backpack carriage. •An inflection point in the energetic cost between 20 kg and 40 kg mass has been previously found.•Methodological protocol differences hinder comparisons among studies.•More specialized research of backpack carriage is necessary in order to understand its implications on human performance.