The extra strain caused by the heat during exercise has been extensively documented by previous literature. Regular training in hot environments induces cardiovascular, haematological, sudomotor, and metabolic adaptations. These are characterised by reduced cardiovascular strain and core body temperature, increased sweat rate and improved fluid balance. Collectively, these adaptations are termed heat acclimation and improve exercise performance in hot environments. Due to these adjustments it is possible that heat acclimation may improve performance in moderate environments, however, previous studies have not included an adequate control group and have only compared highly trained athletes. The purpose of this study was to investigate whether heat stress-induced acclimation improves submaximal and maximal exercise in moderate environments. In a randomised, matched control group study, eighteen healthy males completed maximal and submaximal aerobic tests, followed by an 11-day training protocol, consisting of 60 minutes of incline walking each day on a treadmill at 50% of VO2max in either a hot (35°C, 45% RH) or moderate (18°C, 53% RH) environment. Maximal VO2, submaximal VO2, heart rate and lactate were measured to monitor changes pre and post training. Rectal temperature, heart rate, plasma volume, forearm blood flow, whole body sweat rate, local sweat rate, and perceptual measures were taken throughout the 60 minutes of walking over the 11-day training period, in combination with resting heart rate and blood pressure. The exercise protocol improved maximal aerobic capacity in both conditions (Δ+4±2 and Δ+5 ± 2 mL/kg/min for control and heat group, respectively p<0.001), although, additional heat stress did not improve maximal aerobic capacity above exercise alone. The exercise protocol, in both environments, lowered submaximal heart rate (Δ-6 ± 11 and Δ-6 ± 6 beats/min at 50% of VO2max, p=0.008) but not submaximal blood lactate (p = 0.2). Training lowered resting heart rate (Δ-4 ± 5 and Δ-2 ± 6 beats/min, p<0.001) and core temperature (Δ-0.1 ± 0.2°C and Δ-0.3 ± 0.2°C, p=0.04). Compared with the first training bout, perceived exertion after 60 minutes of exercise was reduced (Δ-0.9 ± 0.7 and Δ-1.1 ± 1.3 aU, p <0.001), but forearm blood flow was increased (Δ+0.4 ± 1.5 and Δ+1.5 ± 4.3 mL/100 mL tissue/min p=0.05). Additionally, only the heat group demonstrated an increased whole body sweat rate (Δ+0.1 ± 0.1 L/hour, p=0.01), and improved thermal comfort (Δ+0.4 ± 0.5 aU, p=0.02). Eleven days of exercise at 50% of VO2max, regardless of environment, can improve maximal and submaximal performance in a moderate environment and induce positive cardiovascular adjustments, although eleven days of exercise in 35°C can induce heat acclimation, illustrated through an increase in whole body sweat rate, and a reduction in core temperature.