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This study aimed to investigate whether the use of short-duration (SHORT) isometric midthigh pull (IMTP) trials resulted in greater reliability and magnitude of time-dependent force-time characteristics than traditionally performed IMTP trials (TRAD). Fourteen subjects with > 6 months' training experience with the power clean volunteered to take part in the study. Subjects performed five ∼1-second IMTP trials (SHORT) and five 5-second IMTP trials (TRAD). SHORT resulted in substantially more reliable rate of force development (RFD) measures (intraclass correlation coefficient [ICC] = 0.97–0.99; coefficient of variation [CV] = 2.6–7.0%), particularly during time bands from force-onset to 150 ms, compared with TRAD when trials were selected for analysis based on peak force (ICC = 0.66–0.83; CV = 14.1–38.5%). Selecting TRAD trials based on RFD0-200 resulted in similar reliability compared with SHORT of those same epochs (ICC = 0.97–0.99; CV = 2.5–7.8%). Furthermore, SHORT resulted in significantly greater force at specific time points, RFD, and impulse compared with TRAD trials (p = 0.001–0.033; g = −0.16 to −0.66). Based on these results, strength and conditioning professionals should use specific testing protocols (i.e., TRAD and SHORT) depending on the component of an athlete's force-generating capacity that they wish to assess and remain aware of the effect analysis choices they have on the reliability of IMTP force-time characteristics.

The aim of this study was to assess the agreement of three different automated methods of identifying force-onset (40 N, 5 SDs, and 3 SDs) with manual identification, during the isometric mid-thigh pull (IMTP). Fourteen resistance-trained participants with > 6 months experience training with the power clean volunteered to take part. After three familiarisation sessions, the participants performed five maximal IMTPs separated by 1 min of rest. Fixed bias was found between 40 N and manual identification for time at force-onset. No proportional bias was present between manual identification and any automated threshold. Fixed bias between manual identification and automated was present for force at onset and F150. Proportional but not fixed bias was found for F50 between manual identification and all automated thresholds. Small to moderate differences (Hedges g = −0.487- −0.692) were found for F90 between all automated thresholds and manual identification, while trivial to small differences (Hedges g = −0.122—−0.279) were found between methods for F200 and F250. Based on these results, strength and conditioning practitioners should not use a 40 N, 5 SDs, or 3 SDs threshold interchangeably with manual identification of force-onset when analysing IMTP force–time curve data.

peer-reviewed, PURPOSE: To examine the reliability and usefulness of the isometric midthigh pull (IMTP) and isometric squat (ISqT) performed at the same knee and hip angles. The scores produced in each test were compared to determine the magnitude of differences between tests. METHODS: Twenty-six male and female athletes (age, 23.6 [4.3] y; height, 1.75 [0.07] m; and body mass, 68.8 [9.7] kg) performed 2 maximal repetitions of the IMTP and ISqT following a specific warm-up. RESULTS: Maximum force, absolute peak force (PF), relative PF, allometrically scaled PF, rate of force development (0-200 and 0-250 ms), and impulse (0-300 ms) were deemed reliable (intraclass correlation coefficient [ICC] ≥.86 and coefficient of variation [CV] ≤9.4%) in the IMTP and ISqT based on predetermined criteria (ICC ≥.8 and CV ≤10%). Impulse (0-200 and 0-250 ms) was reliable in the ISqT (ICC ≥.92 and CV ≤9.9%). Participants produced significantly (P < .05) greater PF and impulse (0-300 ms) during the ISqT compared with the IMTP. When split by sex, female participants produced significantly greater PF (P = .042) during the ISqT, with no significant differences among male participants (P = .245). Both tests are capable of detecting changes in performance in maximum force and absolute PF. CONCLUSIONS: Both tests are reliable for non-time-dependent maximal strength measures when measured at the same knee and hip angles. The ISqT may be preferred when coaches want to test an athlete's true maximum lower-limb strength, especially female athletes, ACCEPTED, peer-reviewed

Seventeen strength and power athletes (n = 11 males, 6 females; height: 177.5 ± 7.0 cm, 165.8 ± 11.4 cm; body mass: 90.0 ± 14.1 kg, 66.4 ± 13.9 kg; age: 30.6 ± 10.4 years, 30.8 ± 8.7 years), who regularly performed weightlifting movements during their resistance training programs, were recruited to examine the effect of altering body posture and barbell position on the between-session reliability of force-time characteristics generated in the isometric mid-thigh pull (IMTP). After participants were familiarised with the testing protocol, they undertook two testing sessions which were separated by seven days. In each session, the participants performed three maximal IMTP trials in each of the four testing positions examined, with the order of testing randomized. In each position, no significant differences were found between sessions for all force-time characteristics (p = >0.05). Peak force (PF), time-specific force (F50, F90, F150, F200, F250) and IMP time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) were reliable across each of the four testing positions (ICC ≥ 0.7, CV ≤ 15%). Time to peak force, peak RFD, RFD time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) and peak IMP were unreliable regardless of the testing position used (ICC =15%). Overall, the use of body postures and barbell positions during the IMTP that do not correspond to the second pull of the clean have no adverse effect on the reliability of the force-time characteristics generated.

peer-reviewed, DIAGNOSTIC TESTING OF VARIOUS POINTS ON THE FORCEVELOCITY CURVE, SUCH AS MAXIMUM STRENGTH AND RUNNING SPEED TESTS, IS USED TO IDENTIFY ATHLETES’ STRENGTHS AND WEAKNESSES. DURING THE IMPLEMENTATION OF THESE TESTS, COACHES TYPICALLY USE VERBAL INSTRUCTIONS IN AN ATTEMPT TO ENSURE THE ATHLETE ACHIEVES THE HIGHEST RESULT POSSIBLE. RESEARCHERS HAVE SHOWN THAT OPTIMAL MOTOR SKILL PERFORMANCE IS OFTEN ACHIEVED WHEN VERBAL INSTRUCTIONS DIRECT ATTENTION EXTERNALLY. THIS ARTICLE REVIEWS THE CURRENT RESEARCH ON THE APPROPRIATE ATTENTIONAL FOCUS FOR TESTS, WHICH ASSESS ASPECTS OF THE FORCE-VELOCITY CURVE. BASED ON AN ANALYSIS OF THE EXISTING SCIENTIFIC LITERATURE, PRACTICAL APPLICATIONS ARE PROVIDED FOR COACHES, ACCEPTED, peer-reviewed

This is an Accepted Manuscript of an article published by Taylor & Francis in SPORTS BIOMECHANICS on 22/09/2021, available online: https://doi.org/10.1080/14763141.2021.1974532

Brady, C. J., Harrison, A. J., Flanagan, E. P., Haff, G. G., & Comyns, T. M. (2019). The relationship between isometric strength and sprint acceleration in sprinters. International Journal of Sports Physiology and Performance, 15(1), 38-45. https://doi.org/10.1123/ijspp.2019-0151

Guppy, S., Brady, C., Kotani, Y., Stone, M., Medic, N., & Haff, G. (2018). The Effect of Altering Body Posture and Barbell Position on the Between-Session Reliability of Force-Time Curve Characteristics in the Isometric Mid-Thigh Pull. Sports, 6(4), 162. Available here

Guppy, S. N., Brady, C. J., Kotani, Y., Stone, M. H., Medic, N., & Haff, G. G. (2019). Effect of altering body posture and barbell position on the within-session reliability and magnitude of force-time curve characteristics in the isometric midthigh pull. The Journal of Strength & Conditioning Research, 33(12), 3252-3262. Available here

peer-reviewed, Introduction: In recent years, the popularity of multi-joint isometric strength testing has increased dramatically. The reliability of variables produced from the force-time curve is conflicting in the literature, and the reporting of reliability is not standardised across the research. The relationship of the isometric mid-thigh pull (IMTP) and isometric squat (ISqT) to sprint performance has been examined in field sports, including soccer and rugby, but there is a lack of research on track and field sprint athletes and hurling players. Further, there is no research examining how isometric strength relates to sprinting kinematics. Aim: To determine and compare the reliability of the IMTP and ISqT and investigate the relationship between isometric strength and sprint performance in track and field sprinters and field sport athletes. Methods: Study one involved a narrative review of the current literature to determine the level of reliability of the IMTP and ISqT and the reporting of normative data. Study two measured the reliability and usefulness of the IMTP and ISqT performed at the same knee and hip angles and determined the magnitude of differences between tests. Study three examined the relationship between the IMTP and ISqT and sprint acceleration performance among track and field sprinters. Study four explored the relationship of the IMTP and sprint kinematics among male sprinters. Study five examined the relationship between the ISqT, countermovement jump (CMJ) and reactive strength index (RSI) and sprint performance in hurling players and determined if principal component analyses (PCA) could be used to reduce the dataset to independent factors. Results: Study one demonstrated that peak force is the most reliable measure and can be used to determine maximum strength capabilities. Study two identified that the same measures from the force-time curve were reliable in both the IMTP and ISqT and both tests are capable of detecting changes in performance of peak

peer-reviewed, Introduction: In recent years, the popularity of multi-joint isometric strength testing has increased dramatically. The reliability of variables produced from the force-time curve is conflicting in the literature, and the reporting of reliability is not standardised across the research. The relationship of the isometric mid-thigh pull (IMTP) and isometric squat (ISqT) to sprint performance has been examined in field sports, including soccer and rugby, but there is a lack of research on track and field sprint athletes and hurling players. Further, there is no research examining how isometric strength relates to sprinting kinematics. Aim: To determine and compare the reliability of the IMTP and ISqT and investigate the relationship between isometric strength and sprint performance in track and field sprinters and field sport athletes. Methods: Study one involved a narrative review of the current literature to determine the level of reliability of the IMTP and ISqT and the reporting of normative data. Study two measured the reliability and usefulness of the IMTP and ISqT performed at the same knee and hip angles and determined the magnitude of differences between tests. Study three examined the relationship between the IMTP and ISqT and sprint acceleration performance among track and field sprinters. Study four explored the relationship of the IMTP and sprint kinematics among male sprinters. Study five examined the relationship between the ISqT, countermovement jump (CMJ) and reactive strength index (RSI) and sprint performance in hurling players and determined if principal component analyses (PCA) could be used to reduce the dataset to independent factors. Results: Study one demonstrated that peak force is the most reliable measure and can be used to determine maximum strength capabilities. Study two identified that the same measures from the force-time curve were reliable in both the IMTP and ISqT and both tests are capable of detecting changes in performance of peak

peer-reviewed, The purpose of this study was to compare peak force produced during the isometric midthigh pull (IMTP) and isometric squat (IsoSquat), performed at the same knee and hip angles (135 – 140°) and determine the reliability of both tests. Following a specific warmup, 22 international athletes from different sports performed 2 maximal effort tests of both the IMTP and IsoSquat. Peak force achieved during the IsoSquat was significantly greater (p = 0.01) than peak force achieved during the IMTP. Both tests were highly reliable for peak force (ICC ≥ 0.97:CV ≤ 5 %). Therefore, strength and conditioning coaches can select either test when examining lower extremity maximum strength. However, the IsoSquat produces higher peak force values and this may be a more accurate reflection of the athlete’s maximum strength.

peer-reviewed, Seventeen strength and power athletes (n = 11 males, 6 females; height: 177.5 ± 7.0 cm, 165.8 ± 11.4 cm; body mass: 90.0 ± 14.1 kg, 66.4 ± 13.9 kg; age: 30.6 ± 10.4 years, 30.8 ± 8.7 years), who regularly performed weightlifting movements during their resistance training programs, were recruited to examine the effect of altering body posture and barbell position on the between-session reliability of force-time characteristics generated in the isometric mid-thigh pull (IMTP). After participants were familiarised with the testing protocol, they undertook two testing sessions which were separated by seven days. In each session, the participants performed three maximal IMTP trials in each of the four testing positions examined, with the order of testing randomized. In each position, no significant differences were found between sessions for all force-time characteristics (p = >0.05). Peak force (PF), time-specific force (F50, F90, F150, F200, F250) and IMP time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) were reliable across each of the four testing positions (ICC ≥ 0.7, CV ≤ 15%). Time to peak force, peak RFD, RFD time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) and peak IMP were unreliable regardless of the testing position used (ICC = <0.7, CV = >15%). Overall, the use of body postures and barbell positions during the IMTP that do not correspond to the second pull of the clean have no adverse effect on the reliability of the force-time characteristics generated.