Estimating maximal strength in contemporary dancers : the compatability of a single leg squat ‘repetitions-to-fatigue protocol’ with existing one repetition maximum equations / Khyle Eccles (2017)

There is currently no lower body maximal strength testing protocol with specific considerations to a contemporary dance population. This study looked to address this using a single leg squat (SLS) protocol and one repetition maximum (1RM) prediction equations. Eighteen 1RM prediction equations were identified that used ‘load’ and ‘repetition’ in their calculation. Body mass was used for the ‘load’, and repetitions were input as total combined repetitions, calculated as a combined 0.5 fraction of the repetitions on each leg (i.e. [right leg repetitions x 0.5] + [left leg repetitions x 0.5]). Three SLS protocols were proposed, with varying cadences (Protocol 1: no cadence, Protocol 2: medium, and Protocol 3: slow). The data from each protocol was entered in to each of the eighteen equations, providing a total of fifty-four equation/protocol combination (EPC) results, which were then compared against a maximum isometric voluntary contraction (MIVC) squat reference test, representing a squat 1RM; and estimated peak power for external reliability.

EPC using the slow cadence had the best direct correspondence with the MIVC. Statistical analysis showed large ranges over all EPC, showing Intraclass correlation coefficients ranging from poor to strong against the MIVC (ICC = -0.079 – 0.678), similar for internal consistency (a = -0.083 – 0.761), and poor to near perfect external reliability (r = -0.47 – 0.94).

Results showed that the Welday equation using Protocol 2 had the best direct correspondence with the MIVC data and presented the greatest overall consistency. However, it only predicted 38% of participants MIVC results. The variance in correlations is likely due to the inability of SLS protocols to elicit a muscular effort great enough to keep repetitions below ten, as required for reliable estimation.

In conclusion, the SLS protocols in combination with existing 1RM prediction equations, were unsuccessful in producing a sufficiently accurate estimation of maximal strength. Future research should investigate ways to increase the effort required to perform a SLS protocol for use in prediction equations; and continue to explore the testing of maximal strength in dancers.