## 2 Materials and Methods  
Eleven females (mean \(\pm\) SD; age: 21.5 \(\pm\) 1.2 years, height 1.66 \(\pm\) 0.051 m and body mass 59.24 \(\pm\) 8.11 kg) and thirteen males (age 22.3 \(\pm\) 1.4 years, height 1.80 \(\pm\) 0.076 m and body mass 73.48 \(\pm\) 6.89 kg) participated in this single cohort, repeated measures, pre-post study. Sample size calculation was based on [PERSON] and colleagues' [19] kinematic results, with an alpha of 0.05 and 90% power. All participants gave verbal and written consent and completed an inclusion criteria questionnaire prior to participation. Participant inclusion was based on the following criteria: age (18-30 years) with regular participation (at least twice per week) in an organised sport or physical activity. Participants with a history of lower limb injury within six months prior to testing, those who had received lower limb surgery, were hypersensitive to the cold or had been diagnosed with Reynaud's Disease were excluded from this study. These exclusion criteria were developed for safety reasons, due to the high-impact nature of the movement tasks examined and the prolonged exposure to a low environmental temperature. This study was approved by the Institutional Human Research Ethics Committee (HEAG-H 34_2012). Data were collected in 2013; however, due to a number of challenging situations, these data were not analysed until 2020. The contemporary nature of this study though will be addressed in the Discussion. A familiarisation session was conducted prior to the commencement of testing. In this session, we showed potential participants the jumping and landing procedures and they were allowed to practice their jumping and landing. We also allowed them to experience the cold environment for 10 min to ensure they were comfortable with the exposure. We used a thermal comfort scale (which is detailed later) to judge the comfort of the participants. Any participant who scored lower than 2 on the scale during the familiarisation was excluded from this study. Lastly, anthropometric measurements (i.e., height and body mass) were taken during familiarisation testing. Participants were tested on three separate occasions (each occasion represented one of the three conditions) with each testing session interspersed by seven days. During a testing session, either a full-length, next-to-skin, lower body compression garment (Figure 1C) (S400 snow compression, Skins, Sydney, NSW, Australia; henceforth termed \"compression garment\"), a full-length, next-to-skin, lower body thermal garment (Figure 1B) (Polypropylene thermal underwear, China; henceforth termed \"thermal garment\") or a pair of conventional running shorts (Figure 1A) (Sports, Kmart Australia Limited, Mulgrave, VIC, Australia; henceforth termed \"control garment\") were allocated to the participant. The sizing of the compression garment used was in accordance with the manufacturer's guidelines while the thermal and control garments were self-determined by the participant. Participants also wore standardised leather boots (Taipan Footwear, Preston, VIC, Australia) to mimic the restricted ankle movement of ski or snowboard boots and a cotton, short-sleeved t-shirt. The order of the conditions was randomised for participants via a random number generator in Microsoft Excel v15. Prior to testing, 23 retro-reflective markers were attached to the participant. The marker positions were adopted from previous work involving drop landing and dynamic knee valgus, which allowed three-dimensional rotations of the knee as well as the participant's jump height (from the pelvis) to be quantified [20]. At the commencement of testing, participants performed five countermovement jumps (CMJ) followed by five drop landings (DL) from a height of 0.9 m. Hands were held akimbo during the CMJ with a 10 s rest provided between each jump. Drop landings were initiated by taking a step off a 0.9 m platform and landing simultaneously with both feet.