# Effects of Introducing Rest Intervals in Functional Fitness Training
## 4 Discussion  
In this study, we compared a standard FFT workout with RFT methodology and one including the same exercises in which subjects rested for 1 min after each round (three breaks in total). In both protocols, exercise repetitions had no time limit; rather, each individual conducted all exercises as quickly as possible but at a pace set by themselves. Having analyzed all the data obtained, our study's most significant findings were as follows: (1) cardiorespiratory intensities of both FFT protocols measured just after their completion were both above 95% age-predicted HR and no significant differences were observed in RPE post-exercise (~15-15.5), which was considered \"hard\"; (2) similar mean HR, equivalent to 90% age-predicted HR, and similar workout durations (~13 min) were observed in the standard and adapted FFT groups; (3) jump ability post-exercise was significantly reduced in both FFT groups; (4) at 3 min post-exercise, blood lactate levels were high in both FFTs (>13 mmol\(\cdot\)L\({}^{-1}\)), although these levels were significantly lower in FFTadapted; and (5) RPE 3 min after the end of each FFT workout was \"moderate\", although significantly reduced in FFTadapted. In addition, no differences were observed in any of the CMJ jump variables between the two groups. Considering the CMJ test quantifies neuromuscular fatigue through several mechanical variables [33; 34], we could argue that both protocols lead to a lowered capacity of the muscles to generate strength regardless of rest intervals. It is likely that the intensity of effort and duration of each workout will give rise to structural damage in tendons, compromising jump capacity [30; 35; 36; 37] and leading to a feeling of fatigue and impaired muscle response in the individual. These jump test data are in agreement with those reported in the literature. In our FFTstandard group, a significant reduction of 6.8% in jump height was observed, which is similar to the findings of a FFT study after two workouts of the day (WODs)--\"Cindy\" (~6.5%) and \"Power clean\" (~7.4%) [30]. In contrast, in the metabolic conditioning WOD (8 sets \(\times\) 20 skip rope double-unders/10 s rest), jump height loss was only \(-\)3.6% [30]. Given the rest intervals established between exercise sets, these data could resemble those observed in our FFTadapted protocol (~4.5%), and effectively, height losses were lower than those of the other FFT WODs. Maximum takeoff velocity losses were \(-\)2.4% in FFTstandard and \(-\)1.6% in FFTadapted. These losses in the standard FFT are similar to those of the Cindy and power clean (~2.7% and ~3.1%, respectively) WODs of the study by [PERSON] et al. (2017) [30], and our adapted FFT losses are similar to that of the skip rope double-unders WOD (~1.2%). For average power, we recorded a value of \(-\)4% for FFTstandard, which is similar to that of the Cindy WOD (~4%), although there was a greater jump height loss in the power clean WOD (~7.35%). In the FFTadapted group, average power loss was \(-\)3.3%, which is slightly higher than that reported for the skip rope double-unders WOD with rest intervals (\(--\)2%). In another study in which jump ability was examined in the FFT WODs Cindy, power clean, and skip rope double-unders [38], similar results were obtained to those observed here and those of [30], with the exception of mean velocity in the Cindy WOD (\(-\)13.8%) and average power in the power clean WOD (\(\sim\)\(-\)8%). Accordingly, given the differences between the FFT exercise protocols and FFT WODs along with their durations, jump capacity losses were similar. If we examine mean HRs recorded across all FFT WODs--178 bpm (92.5% HRmax) for Cindy and double-unders and 172 bpm (89% HRmax) for power clean, these were all around or above 90% age-predicted HR [38], and reported blood lactate levels were 10-12 mmol-L\({}^{-1}\)[30,38]. In another study, [PERSON] et al. (2015) [39] reported an HRs of 182 bpm (97% HRmax) and blood lactate concentrations of 14.5 mmol-L\({}^{-1}\). Another recent study by [PERSON] et al.