A low-volume Nordic hamstring curl programme improves change of direction ability, despite no architectural, strength or speed adaptations in elite youth soccer players

Figures & data

Figure 1. Individual participant response for eccentric hamstring strength peak torque at 60°s^–1 (A), 180°s^–1 (B) and 270°s^–1 (C).

Table 1. Overview of primary, secondary and performance outcome measures from pre and post testing sessions. Data presented as mean SD unless otherwise stated.

METRIC	PRE	POST	MEAN DIFFERENCE	INFERENCE	SEM	MDD
IKD PT 60°s-^1 (Nm^−1)	145.82 ± 40.99	155.25 ± 41.24	9.43	Small	16.45	45.59
IKD PT 180°s-^1 (Nm^−1)	156.62 ± 37.33	171.34 ± 35.27	14.72	Small	14.27	39.56
IKD PT 270°s-^1 (Nm^−1)	150.94 ± 36.05	157.77 ± 38.17	6.83	Trivial	15.87	44.00
IKD APT 60°s-^1 (°)	42.00 ± 11.90	40.93 ± 10.19	-1.07	Trivial	4.36	12.07
IKD APT 180°s-^1 (°)	37.80 ± 5.22	35.90 ± 3.54	-1.90	Trivial	1.96	5.42
IKD APT 270°s-^1 (°)	56.50 ± 16.48	52.92 ± 20.78	-3.58	Small	7.76	21.52
BF^lh MT (cm)	2.28 ± 0.41	2.23 ± 0.26	-0.05	Trivial	0.15	0.43
SM MT (cm)	2.89 ± 0.45	3.02 ± 0.42	0.13	Small	0.20	0.54
ST MT (cm)	2.73 ± 0.49	2.84 ± 0.38	0.11	Small	0.19	0.52
BF^lh FL (cm)	7.61 ± 1.27	7.82 ± 1.06	0.21	Trivial	0.49	1.35
BF^lh PA (°)	17.94 ± 3.96	17.33 ± 3.12	-0.61	Trivial	1.43	3.97
Mean COD (s)	2.49 ± 0.07	2.43 ± 0.08*	-0.06	Large	0.02	0.05
Sprint 5m (s)	0.97 ± 0.04	0.96 ± 0.05	-0.01	Small	0.02	0.04
Sprint 10m (s)	1.67 ± 0.06	1.68 ± 0.06	0.01	Trivial	0.02	0.05
Sprint 20m (s)	2.92 ± 0.09	2.93 ± 0.11	0.01	Trivial	0.03	0.08

IKD, isokinetic dynamometer; PT, peak torque; APT, angle of peak torque; BF^lh, biceps femoris long head; MT, muscle thickness; SM, semimembranosus; ST, semitendinosus; FL, fascicle length; PA, pennation angle; SEM, standard error of measurement; MDD, minimal detectable difference. * Denotes a significant difference between pre and post intervention

Figure 2. (a) Individual participant response for fascicle length of biceps femoris long head muscle. (b) Individual participant response for pennation angle of biceps femoris long head muscle.

Figure 3. Individual participant response for linear sprint speed.

Figure 4. Individual participant response for mean change-of-direction speed. *Denotes statistical significance (p < 0.05).