Hamstring musculotendon mechanics of prospectively injured elite rugby athletes

Figures & data

Figure 1. Musculotendon (MT) strain (%), velocity (m/s), force (N/kg and (N/cm3) and power (W/kg) for each of the four hamstring muscles, across the late swing phase, for athletes a and B. Late swing phase was defined as beginning at peak knee flexion (0%) and ending at foot contact (100%).

Table 1. Peak MTU strain, velocity, force and power absorption during the late swing phase for each hamstring muscle.

	BFlh	BFsh	SM	ST
Athlete A
Peak strain (% change from static pose)#	7.07	−3.39	4.77	4.73
Resting length (m)*	0.47	0.25	0.46	0.51
Peak lengthening velocity (m/s)	−0.99	−0.59	−0.88	−1.05
Peak force/BW (N/kg)	35.40	7.70	40.80	3.86
Peak force/PCSA (N/PCSA)	120.80	42.71	91.91	20.73
Peak power absorption (W/kg)	−17.38	−2.78	−12.82	−1.98
Athlete B
Peak strain (% change from static pose)#	9.31	−2.60	7.04	7.15
Resting length (m)*	0.49	0.26	0.48	0.53
Peak lengthening velocity (m/s)	−0.85	−0.66	−0.77	−0.93
Peak force/BW (N/kg)	30.06	9.22	43.03	4.35
Peak force/PCSA (N/PCSA)	109.38	58.53	110.89	26.51
Peak power absorption (W/kg)	−14.34	−2.76	−22.55	−0.96

BFlh, biceps femoris long head; BFsh, biceps femoris short head; SM, semimembranosus; ST, semitendinosus. Note: Late swing phase was defined as beginning at peak knee flexion and ending at foot contact.

#Positive strain values reflect an increase in length from the resting length, and negative values represent a decrease in length from the resting length.

*MTU length during the static pose.

Table A1. Generic properties of the hamstring muscles used in the current study.

	BFlh	BFsh	SM	ST
Maximum isometric force (N) ^#	2757	1170	4622	1241
Optimal fibre length (m) *	0.098	0.110	0.086	0.193
Pennation angle (deg) *	10.1	15.1	14.6	13.8
Tendon slack length (m)	0.333	0.106	0.335	0.247

BFlh, biceps femoris long head; BFsh, biceps femoris short head; SM, semimembranosus; ST, semitendinosus.

#Maximum isometric force after being scaled up by a factor of 2.1.

*Based on data published by Ward et al. (2009).

Table A1. Residual forces (N) applied at the pelvis during inverse dynamics pre and post RRA.

	FX Max			FY Max			FZ Max
	Pre	Post	% Reduction	Pre	Post	% Reduction	Pre	Post	% Reduction
Athlete A	864.2	18.4	97.9	1599.6	159.5	90.0	871.3	45.3	94.8
Athlete B	952.1	12.4	98.7	2013.6	158.9	92.1	1282.3	30.3	97.6
Ave All	908.2	15.4	98.3	1806.6	159.2	91.2	1076.8	37.8	96.5

Table A2. Residual moments (Nm) applied at the pelvis during inverse dynamics pre and post RRA.

	MX Max			MY Max			MZ Max
	Pre	Post	% Reduction	Pre	Post	% Reduction	Pre	Post	% Reduction
Athlete A	357.7	72.4	79.7	524.6	153.0	70.6	299.6	245.0	18.2
Athlete B	586.2	67.1	88.6	449.6	83.8	81.3	315.8	174.4	44.0
Ave All	472.0	69.8	85.2	487.1	118.4	75.7	307.7	209.7	31.9

Table A3. Kinematic adjustments resulting from RRA in order to reduce the required residual loads.

	Translations (cm)*		Rotations (deg)^#
	Max	RMS	Max	RMS
Athlete A	1.8	1.2	1.3	0.8
Athlete B	2.9	1.7	1.6	1.0
Ave All	2.4	1.4	1.4	0.9

*Translations in the x, y and z direction at the pelvis.

#Rotations at the pelvis and right leg.

Table A4. Kinematic errors resulting from CMC. These represent the difference between experimental generalized coordinates and those predicted by the model.

	Translations (cm)*		Rotations (deg)^#
	Max	RMS	Max	RMS
Athlete A	0.3	0.2	2.0	1.2
Athlete B	0.2	0.1	1.5	0.8
Ave All	0.3	0.1	1.8	1.0

*Translations in the x, y and z direction at the pelvis.

#Rotations at the pelvis and right leg.

Table A5. Residual forces (N) and moments (Nm) applied at the pelvis during CMC.

	FX		FY		FZ		MX		MY		MZ
	Max	RMS	Max	RMS	Max	RMS	Max	RMS	Max	RMS	Max	RMS
Athlete A	164.7	69.1	102.3	54.0	140.7	56.4	135.2	58.0	247.7	116.7	105.7	46.9
Athlete B	154.0	48.5	96.0	43.9	174.2	71.5	110.8	50.4	189.1	94.6	74.2	31.6
Ave All	159.3	58.8	99.1	48.9	157.5	64.0	123.0	54.2	218.4	105.7	89.9	39.2

Table A6. Reserve actuator contribution (%) to joint torques in the leg of interest (right leg) during CMC.

	Lumbar			Hip			Knee	Ankle
	Flexion/Extension	Bending	Rotation	Flexion/Extension	Adduction/Abduction	Internal/External Rotation	Flexion/Extension	Flexion/Extension
Athlete A	0.3	0.3	0.2	1.2	20.1	84.0	10.1	0.0
Athlete B	0.3	0.2	0.2	0.9	14.7	103.6	4.4	0.0
Ave All	0.3	0.2	0.2	1.0	17.4	93.8	7.2	0.0

Figure A1. Predicted muscle activations for the hamstrings across the late swing phase.

Data availability statement

The data that supports the findings of this study are available in the appendices of this article.