Background and Purpose: Resistance training is the foundation for increasing muscular strength as well as cardiorespiratory and metabolic fitness and increasing or preserving the capacity to produce power. These resistance training benefits are relevant to the health of the general population and also elite and recreational athletes; particularly those undergoing rehabilitation and as a means of protecting against sports injuries. However, the optimal relationship between resistance training intensity and subsequent physiological improvements remains to be defined. Over the past few decades, the ‘Critical Power’ (CP) concept exemplifies the link between fatigue or exhaustion and performance. In this regard, sports scientists and human physiologists have always used this concept as a link between the development of fatigue/exhaustion (and its mechanistic portents) and exercise performance as a means to prescribe efficient training programs and monitor progress. The present study aimed to a comparison of 1- repetition maximum and the number of repetitions until exhaustion during a squat movement based on two and three critical power components modeling in trained women
Materials and Methods: Seven trained women (age: 20.11 ± 1.15 years, body mass index: 19.6 93 0.93) Performed Six sets of barbell squats at different intensities based on the percentage of 1-repetition maximum, On six separate days with a rest of at least 24 hours. The weights were selected so the activity lasted about 3-12 minutes. Total activity time to exhaustion and movement rate was estimated using a Stopwatch and distance using Kinovea software.
Results: A linear two-parameter model of CP was accurately able to model exhaustive squatting data based on the plotting total work accomplished versus time-to-exhaustion (r2=0.89±0.09) and paired samples t-tests demonstrated that the actual number of repetitions to failure was not different from the predicted values (P > 0.05). The hyperbolic three-parameter model of CP was also able to model these data based on plotting time-to-exhaustion against total output power (0.90±0.06) and there was also no considerable difference between the actual number of repetitions to failure and those predicted by this model (P > 0.05). Additionally, there weren’t any significant differences between the measured one-repetition maximum and those predicted by the hyperbolic model (P > 0.05). However, the linear two-parameter model was not able to predict one repetition maximum (p<0.05). There was no significant difference between the predicted values of 1-repetition maximum based on hyperbolic modeling and the values measured using the Brzycki method (p<0.05). However, the two-component linear model was not able to predict this variable (P < 0.05).
Conclusion: The two-component linear and three-component hyperbolic models can be generalized to the squat movement to exhaustion. These models also have a high ability to predict the number of repetitions to the exhaustion in squat movement. However, 1 repetition maximum was predictable only with the hyperbolic three-component model.