High-intensity functional training (HIFT) comprises a variety of functional movements and exercises executed at a high intensity (Haddock et al., 2016). In recent times, functional training, mostly executed with the individual’s own bodyweight, is increasing in popularity. For recreationally active individuals, these traditional exercise modalities may be perceived as boring due to little or no variation, which could have a negative impact on training adherence, as “lack of enjoyment” is a commonly cited barrier for engaging in regular exercise (Bartlett et al., 2011).
Typically, this involves using classical exercise modalities such as, running, cycling and rowing (Buckley et al., 2015).
Considering adherence to classic MICT is typically low, HIIT is a more time-efficient training modality and may therefore be the method of choice for increased encouragement in exercise participation (McRae et al., 2012).Įndurance athletes perform HIIT training to improve sport specific performance (Gist et al., 2015). These data indicated that short duration exercise, which is of a sufficiently high intensity, is capable of inducing favorable training adaptions. ( 1996) demonstrated that short duration (7-8 sets of 20 s exercise, interspersed with 10 s rest the “Tabata protocol”) high-intensity intermittent exercise caused the same, or even greater improvements in aerobic (VO 2max) and anaerobic power as moderate-intensity endurance training (60 min intensity 70% of VO 2max). Recent data suggests that repeated maximal to supramaximal exercise bouts have a similar, or even greater influence on CRF and metabolic adaptions than traditional moderate-intensity continuous training (MICT) (Gist et al., 2014b). Regular physical activity is essential for the prevention of cardiovascular and metabolic diseases (Fealy et al., 2018) and high-intensity interval training (HIIT) is an effective training method to elicit rapid improvements in cardiorespiratory fitness (CRF expressed as maximal oxygen consumption (VO 2max)) (Astorino et al., 2012 Daussin et al., 2008 Gist et al., 2014b). These findings suggest that classic running HIIT and functional HIIT both improve VO 2max and affect muscular endurance to the same extent despite a lower cardiovascular strain in the functional protocol. Muscular endurance (burpees and toes to bar) significantly improved (p =0.004 and p = 0.001, respectively) independent of training modality. However, despite these differences in exercise HR, VO 2max improved similarly (~13% for the HIIT-R versus ~11% for the HIIT-F, p=0.300). Mean and peak HR during the training sessions were significantly different (p = 0.018 and p = 0.022, respectively) between training groups, with HIIT-F eliciting lower HR responses than the HIIT-R.
Training heart rate (HR) data were collected throughout all training sessions. Over a four-week period, both groups performed 14 exercise sessions of either HIIT-R or, HIIT-F consisting of 3-4 sets of low-volume HIIT (8x 20 s, 10 s rest set rest: 5 min). Fifteen healthy, moderately trained female (n = 11) and male (n= 4) participants (age 25.6 ± 2.6 years) were assigned to either running HIIT (HIIT-R n = 8, 6 females, 2 males) or functional HIIT (HIIT-F n = 7, 5 females, 2 males). The purpose of the study was to assess if high-intensity interval training (HIIT) using functional exercises is as effective as traditional running HIIT in improving maximum oxygen uptake (VO 2max) and muscular endurance.