Donovan S. Conley

Peak oxygen deficit predicts sprint and middle-distance track performance

The purpose of this study was to determine the value of the peak oxygen deficit (POD) as a predictor of sprint and middle-distance track performance. POD, peak blood lactate, VO2peak, lactate threshold, and running economy at 3.6 m.s-1 were measured during horizontal treadmill running in 22 male and 19 female competitive runners of different event specialties. Subjects also completed running performance trials at 100, 200, 400, 800, 1500, and 5000 m. Correlations of track performances with POD (ml.kg-1) (-0.66, -0.71, -0.71, -0.62, -0.52, and -0.40) were moderately strong at the sprint and middle distances, accounting for 44-50% of the performance variance at the three shortest distances. Correlations of track performances with peak blood lactate concentration were lower than with POD and accounted for approximately one-half as much of the performance variance (21-26%) at the three shortest distances. Multiple regression analyses indicated that the POD was the strongest metabolic predictor of 100-, 200- and 400-m performance, and that VO2peak was the strongest metabolic predictor of 800-, 1500-, and 5000-m performance. We conclude that the POD is a moderately strong predictor of sprint and middle-distance track performance.

Peak oxygen deficit during one- and two-legged cycling in men and women.

The objectives of this study were to determine the relationships of estimated active muscle mass and gender to anaerobic capacity, as measured by the peak oxygen deficit, and to compare these relationships with those for peak oxygen uptake (VO2peak). Fat-free leg volumes (FFLV), and one- and two-legged cycling peak oxygen deficit and VO2peak were determined in young, physically active men (N = 11) and women (N = 9). For men and women, mean (+/- SD) peak oxygen deficit for one-legged cycling (2.27 +/- 0.30 and 1.18 +/- 0.18 l) was 52% of that for two-legged cycling (4.40 +/- 0.62 and 2.25 +/- 0.28 l). For all subjects and both modes of exercise, there was a strong linear relation between peak oxygen deficit (1) and estimated active muscle mass (FFLV) (r = 0.94). This relation was the same in one- and two-legged cycling, but was different for men and women. For a given FFLV, the peak oxygen deficit was significantly higher (P < 0.05) in men than women by an average of 0.44 l. The relation of peak oxygen deficit to FFLV was significantly stronger than the relation of VO2peak to FFLV (r = 0.80). We conclude: (a) that the peak oxygen deficit is strongly related to the estimated active muscle mass during cycling; (b) that for a given estimated active muscle mass (FFLV), the peak oxygen deficit is higher in men than women; and (c) that the peak oxygen deficit is more strongly related than VO2peak to the estimated quantity of active muscle.

Effects of Low- and High-Volume Stretching on Bench Press Performance in Collegiate Football Players

Molacek, ZD, Conley, DS, Evetovich, TK, and Hinnerichs, KR. Bench press performance in collegiate football players. J Strength Cond Res 24(3): 711-716, 2010-The purpose of this study was to determine the effects of acute low- and high-volume static and proprioceptive neuromuscular facilitation (PNF) stretching on 1-repetition maximum (1RM) bench press. Fifteen healthy male National Collegiate Athletic Association Division II football players (age: 19.9 ± 1.1 years; weight: 98.89 ± 13.39 kg; height: 184.2 ± 5.7 cm; body composition: 14.6 ± 7.4%; and 1RM bench press: 129.7 ± 3.3 kg) volunteered to participate in the study. Subjects completed 5 different stretching protocols integrated with a 1RM dynamic warm-up routine followed by 1RM testing in randomly assigned order. The protocols included (a) nonstretching (NS), (b) low-volume PNF stretching (LVPNFS), (c) high-volume PNF stretching (HVPNFS), (d) low-volume static stretching (LVSS), and (d) high-volume static stretching (HVSS). Two and 5 sets of stretching were completed for the low- and high-volume protocols, respectively. The stretching protocols targeted triceps and chest/shoulder muscle groups using 2 separate exercises. There were no significant differences in 1RM bench press performance (p > 0.05) among any of the stretching protocols NS (129.7 ± 3.3 kg), LVPNFS (128.9 ± 3.8 kg), HVPNFS (128.3 ± 3.7 kg), LVSS (129.7 ± 3.7 kg), and HVSS (128.2 ± 3.7 kg). We conclude that low- and high-volume PNF and static stretching have no significant acute effect on 1RM bench press in resistance-trained collegiate football players. This suggests that resistance-trained athletes can include either (a) a dynamic warm-up with no stretching or (b) a dynamic warm-up in concert with low- or high-volume static or PNF flexibility exercises before maximal upper body isotonic resistance-training lifts, if adequate rest is allowed before performance.

Validation of the 12-min swim as a field test of peak aerobic power in young men.

The purposes of this study were to validate the 12-min swim as a field test of VO2max and to compare its validity with that of the 12-min run. Thirty-six young men completed 12-min swim, 12-min run, tethered swimming (TS) VO2peak, and treadmill running (TR) VO2peak tests within 3 wk. Mean (+/- SD) 12-min swim and run distances were 581 +/- 88 and 2797 +/- 290 m, and mean TS and TR VO2peak values were 50.3 +/- 6.2 and 57.2 +/- 5.5 ml.kg BW-1.min-1, respectively. Correlation coefficients and standard errors of estimate for predictions of TS VO2peak from the 12-min swim (0.40 and 5.7 ml.kg BW-1.min-1) and run (0.74 and 4.2 ml.kg BW-1.min-1) and for predictions of TR VO2peak from the 12-min swim (0.38 and 5.1 ml.kg BW-1.min-1) and run (0.88 and 2.6 ml.kg BW-1.min-1) indicated that the 12-min run was a more accurate predictor of TS or TR VO2peak than the 12-min swim. We conclude that the 12-min swim has relatively low validity as a field test of peak aerobic power and that it should not be considered an equally valid alternative to the 12-min run in young male recreational swimmers. However, the accuracy of predicting VO2peak from the 12-min swim is as good as some other commonly used methods, and, therefore, it may be adequate for fitness classification in situations in which a high level of accuracy is not needed.

Postactivation Potentiation Enhances Upper- and Lower-Body Athletic Performance in Collegiate Male and Female Athletes

Abstract Evetovich, TK, Conley, DS, and McCawley, PF. Postactivation potentiation enhances upper- and lower-body athletic performance in collegiate male and female athletes. J Strength Cond Res 29(2): 336–342, 2015—The purpose of this study was to determine the effect of postactivation potentiation (PAP)-inducing activities in 4 separate studies examining vertical (VJP) and horizontal (HJP) jump performance, shot put performance (SPP), and sprint performance (SP), in National Collegiate Athletic Association Division II athletes. Study 1: 12 male (mean ± SD; age = 20.2 ± 2.0 years; height = 178.1 ± 6.2 cm; weight = 73.3 ± 6.43 kg) and 8 female (age = 20.1 ± 1.0 years; height = 169.6 ± 5.5 cm; weight = 59.8 ± 7.6 kg) track athletes participated in HJP and VJP testing before and after performing a parallel back squat (PBS) at 85% 1 repetition maximum (RM). Study 2: 10 (6 men and 4 women) shot put throwers (age = 20.6 ± 0.7 years; height = 182.1 ± 9.8 cm; weight = 102.8 ± 23.6 kg) participated in SPP testing for control (C), 3RM bench press, and 3RM PBS protocols. Study 3: 7 football players (age = 20.4 ± 1.6 years; weight = 87.8 ± 8.3 kg; height = 184.3 ± 7.2 cm) participated in SP testing before (PBS1) and after (PBS2) performing a 3RM PBS. Study 4: 11 football players (age = 20.3 ± 1.8 years; height = 180.6 ± 7.5 cm; weight = 86.1 ± 12.8 kg) participated in VJP testing for C and 3RM PBS protocols. Results of study 1: There was a significant (p ⩽ 0.05) increase in VJP (PRE = 61.9 ± 12.3 cm; POST = 63.6 ± 11.6 cm) and HJP (PRE = 93.7 ± 11.0 cm; POST = 95.9 ± 11.5 cm). Study 2: SPP after PBS (11.67 ± 1.92 m) was not different vs. C (11.77 ± 1.81), but bench press (11.91 ± 1.81 m) was significantly greater (p ⩽ 0.05) than both PBS and C. Study 3: SP time was significantly lower for PBS2 (4.6014 ± 0.17995 seconds) vs. PB1 (4.6557 ± 0.19603 seconds). Study 4: There was no difference in VJP for C (68.35 ± 2.16 cm) vs. PBS (68.12 ± 2.51 cm). Our data show that a 3RM PBS resulted in significant improvements in VJP, HJP, SPP, and SP in National Collegiate Athletic Association Division II male and female athletes. Strength and conditioning practitioners should potentially alter their warm-up programs to include PAP protocols to enhance performance of power athletes. However, there were nonresponders in each study, and coaches and athletes need to determine whether it is worthwhile to identify nonresponders before implementing PAP protocols.

INTERPRETING NORMALIZED AND NONNORMALIZED DATA AFTER ACUTE STATIC STRETCHING IN ATHLETES AND NONATHLETES

Evetovich, TK, Cain, RM, Hinnerichs, KR, Engebretsen, BJ, and Conley, DS. Interpreting normalized and nonnormalized data after acute static stretching in athletes and nonathletes. J Strength Cond Res 24(8): 1988-1994, 2010-The purpose of this study was to determine the effect of acute static stretching on torque and electromyography (EMG) in female athletes (ATHs) and nonathletes (NONATHs) using both normalized (NORM) and nonnormalized (NONNORM) data. Fifteen ATHs recruited from womens National Collegiate Athletic Association Division II varsity basketball and volleyball teams were paired to 14 NONATHs. Electromyography (μV) was detected over the rectus femoris during isokinetic leg extensions at 60 and 300°·s−1 before (PRE) and after (POST) static stretching. There was a significant main effect for torque (mean ± SD PRE = 81.9 ± 22.7 N·m; POST = 77.0 ± 21.9 N·m) and EMG amplitude (PRE = 767.6 ± 288.6 μV; POST = 664.2 ± 219.3 μV) for PRE compared to POST. For the NORM data, there was a significant decrease in torque for the NONATHs (mean ± SD PRE = 73 ± 12 N·m; POST = 67 ± 12 N·m) but no significant difference for the ATHs (mean ± SD PRE = 65 ± 11 N·m; POST = 66 ± 8 N·m). The NONNORM data indicated that both the ATHs and NONATHs displayed a stretching-induced decrease in torque that may be manifested in a decreased ability to activate the muscle. The NORM data revealed the NONATHs but not the ATHs were hindered in their ability to produce torque as a result of the stretching. Coaches and ATHs may want to carefully consider whether to include stretching in their precompetition routine. When reading the literature, the practitioner should consider the manner in which the data were calculated and analyzed (NORM or NONNORM) because it may affect the conclusions of the study.