Comparison Of Polarized Vs Threshold Training For Vo2Max And Endurance Capacity Improvement In Wistar Rats

The superiority of Polarized Training (POL) vs other training models is questionable due to conflicting results. This could be surpassed by rigorously controlled experimental studies. PURPOSE: Our aim was to compare an eight-week POL vs Threshold Training (THR) protocol on maximal O2 uptake (VO2max) and endurance capacity (EC) in rats. METHODS: Fifteen male Wistar rats (336.1 ± 30.4 g) were divided in three groups: POL (n = 5), THR (n = 5), controls (CON, n = 5), housed in cages with running wheel, 12/12 h inverted light/dark cycle, 23oC, 50-60% humidity, with food and water ad libitum. After two-weeks of treadmill acclimatization, animals were tested for VO2max. The speed corresponding to 60 and 90% VO2max in POL and 50 and 75% VO2max in THR were determined. EC was assessed by a treadmill exhaustion test (10o slope, initial speed 25 m/min, 5 m/min increments every 15 min). Both groups underwent eight-week, 5d/w treadmill running. POL performed 12 min@90%VO2max + 48 min@60%VO2max (80% low intensity/20% high intensity) while THR performed 5 min@50%VO2max + 48 min@75%VO2max (moderate intensity). Training duration was adjusted between groups to ensure similar O2 uptake (POL = 3128 O2 L/day, THR = 3277 O2 L/day; p = .261). CON performed treadmill running 10 min/d, 10 m/min, 5d/w to equalize treadmill stress. At the end of the protocol animals were again assessed for VO2max and EC. RESULTS: At the beginning of the protocol there were no differences between groups in VO2max (p = .051) or EC (p = .069). Although there were no differences in VO2max between POL (80.6 ± 11.3 mL.Kg.min-1) and THR (82.6 ± 9.7 ml.Kg.min-1) at the end of training, VO2max was only higher in THR compared to CON (64.8 ± 2.9 mL.Kg.min-1; p = .042). Both POL (2056 ± 122 m; p < .01) and THR (2134 ± 413 m; p < .01) had a significantly higher EC compared to CON (823 ± 223 m) at the end of the training protocol, but there were no differences in EC between POL and THR. CONCLUSION: There were no differences in VO2max and EC between POL or THR after eight-weeks of training. FCT grants UID/DTP/00617/2020, LA/P/0064/2020 and PTDC/SAU-DES/4113/2020.