Biomechanical comparison of lower limb kinetics and kinematics between lateral lunge and walking and implications for rehabilitation in the healthy

Abstract

Introduction

Lunge exercises are utilized to strengthen the knee before and after knee surgeries, but lack of research on kinetics of lateral lunge has been detected. This study was to investigate whether knee joint moments would be affected by lateral lunge.

Methods

This is a cross-section prospective study. Ten healthy participants performed lateral lunge and normal walking. A motion capture system and force platform were used to collect lower limb movement. Biomechanical parameters, e.g. joint moments and forces, were calculated using a biomechanical model, and the outcomes were statistically compared between lunge and walking.

Results

The results showed that knee moments in lateral lunge were significantly higher by roughly 34% in abduction than in walking; knee force had significantly higher in the lateral direction by roughly 50%; hip moments were significantly higher in external rotation direction by roughly 53% in lunge than in walking. In general, joint angles in the knee and hip were significantly larger in lunge than in walking. However, other parameters in lunge were less than in walking.

Conclusions

These findings provide useful reference to clinicians when prescribing lateral lunge to patients in rehabilitation and to coaches when arranging lateral lunge as an exercise for sportsmen.

Resumen

Introducción

Los ejercicios de zancada se utilizan para fortalecer la rodilla antes y tras las cirugías de rodilla, aunque se ha detectado que se carece de investigación sobre la cinética de la zancada lateral. El objetivo de este estudio fue investigar si los momentos articulares de la rodilla se verían afectados por la zancada lateral.

Métodos

Se trata de un estudio prospectivo transversal, en el que diez participantes sanos realizaron zancada lateral y caminata normal. Se utilizó un sistema de captación de movimiento y una plataforma de fuerza para recopilar el movimiento del miembro inferior. Se calcularon parámetros biomecánicos, como por ejemplo los momentos y fuerzas articulares, utilizando un modelo biomecánico, y se compararon estadísticamente los resultados entre zancada y caminata.

Resultados

Los resultados reflejaron que los momentos de la rodilla en la zancada lateral fueron significativamente más altos en casi un 34% en abducción que en la caminata; la fuerza de la rodilla fue significativamente más alta en dirección lateral en casi un 50%; los momentos de la cadera fueron significativamente más altos en dirección de rotación externa en casi un 53% en zancada que en caminata. En general, los ángulos articulares de rodilla y cadera fueron significativamente más amplios en zancada que en caminata. Sin embargo, otros parámetros de la zancada fueron inferiores que en la caminata.

Conclusiones

Estos hallazgos aportan una referencia útil a los clínicos a la hora de prescribir la zancada lateral a los pacientes en rehabilitación, así como a los entrenadores a la hora de planificar la zancada lateral como ejercicio para los deportistas.

Introduction

From infancy till death, in certain circumstances a person's regular everyday actions are either lunging or walking [1]. Walking serves as a means of transport and is also considered one of rehabilitation programs. Lunge exercises are used to strengthen the knee in both normal and abnormal circumstances before and after knee surgeries [2–4]. There are various types of lunges, including single-sided front lunge, side/lateral lunge, backward lunge, etc. Both lunging and walking have positive effects on rehabilitation [5–7]. Most of the daily motions we perform, such as biking, running, and climbing stairs, involve movements in the sagittal plane, but many movements are also involved in the coronal plane, e.g. basketball or football players often moving side-to-side. Though there are many studies on forward or backward lunge, there is lack of research on kinetics and kinematics of lateral lunge compared to walking [8–11].

A previous study performed a comparative study on walking, reversing, and forward lunge movements [12]. They analyzed the mechanical outcomes of the movements to identify which factors contribute to lunge efficiency and injury risk. A few subjects were recruited in their study that three lunge movements were performed. They concluded that reverse lunge movement produced higher agonist muscle activities with a relatively low moment and maximum knee shearing force when compared to the other lunge techniques, indicating that lunge exercise is a useful technique for strengthening the quadriceps femoris and gluteus maximus. Moreover, another study investigated how forward and lateral lunges changed biomechanically in knee moment and functional measurement [7]. They investigated the differences between three lunges, namely FMS (functional muscle screen) in-line lunge, FL (forward lunge) and LL (lateral lunge). The knee moments were found to be significantly different among three lunges. Also, a study carried out an analysis of the deep lunge and its implications on rehabilitation of back pain from a biomechanical perspective using motion capture system [13]. The muscle activities from the rectus femoris (RF), erector spinae (ES), and tibialis anterior (TA) were recorded with an electromyography system. In the past, studies concluded that deep lunge exercise offers a range of joint flexibility and muscular activity levels, particularly in the ankle dorsi-flexors, back extensor muscles, and knee extensor muscles, and it may be suitable for most patients’ rehabilitation who require increased strength and endurance, particularly those with back discomfort [6,9].

Comparing lateral lunges to ordinary walking, however, has not been done in previous studies, leaving a research gap. Given that walking is an active controlled task and integrates relevant contemporary gait literature [13], it is essential for a valid comparison between walking and a lateral functional task. Therefore, the research question was whether lateral lunge requires higher joint strength than walking or not. Therefore, the primary objective of this current study was to investigate knee peak moments during lateral lunge exercise compared to walking, and secondary objectives were to investigate other kinetic parameters in the lower limb joints. Vicon motion capture system and force platforms were used to collect lateral lunge and normal walking data. The biomechanical parameters in the lower limb joints were calculated. Hopefully, the outcomes make a useful reference to clinicians who proscribe rehabilitation exercise to patients [14].

Methods

This study was approved by the School of Medicine and School of Life Science Research Ethics Committee (SMED-SLS-TPG-20024-24-09). Participants were invited to attend the Motion Analysis Lab for a single session of 60 min for data collection. All participants read participant-information-sheet and signed consent forms before data was collected.

When recruiting, the inclusion criteria were (1) healthy people, (2) aged between 18 and 40, (3) any gender, and (4) individuals without musculoskeletal pathologies of the lower limbs. The exclusion was anyone with self-reported injury or uncomfortable in the lower limbs. Anthropometric measures of height, weight, gender, age, BMI, and leg length were taken.

Equipment used

Vicon® MX system with 10 cameras (Oxford Metrics, Oxford, UK) at 100 Hz was used to collect movements. A set of reflective markers were placed in the body according to Vicon Plug-in-Gait lower limb model with the markers named R/LASI, R/LPSI, R/LTHI, R/LKNE, R/LTBI, R/LANK, R/LTOE, R/LHEE, defined by Vicon Clinical Management System as Fig. 1. Ground reaction forces were measured with an AMTI® OR6-7 force platform (Advanced Mechanical Technology Inc., Watertown, MA, USA) at 1000 Hz. All systems were synchronized via Vicon Nexus software.

Fig. 1.

Right lateral lunge (left) and stick figure in Vicon Nexus interface (right). Note: The upper view: a loading phase: bend knee laterally and descend trunk as low as possible to apply maximum loading in the right side; the lower view: a recovery phase: ascend the body and move the center of mass to the left side.

Tasks

At the beginning, a T-pose was recorded for Vicon Nexus software to calibrate the Plug-in-Gait model. Before performing the exercises, modest warm-ups such as lower limb stretches for the quadriceps and hamstring stretches were conducted. Participants were asked to perform lateral lunge for five trails with the right side to bend knee and descend body laterally as much as possible and walk at comfortable speed at five trails as in Figs. 1 and 2. To define phases, the right foot was on the force platform and the body started to move down as event 1 and the right lateral lunge reaching lowest position as event 2: this phase was loading (descending); and when subjects moved to the left position or similar as event 3: this phase is recovery (ascending) phase. For walking, the first foot strike is on the force platform as event 1, the foot off as event 2 and next foot strike as event 3, i.e. there were two phases, stance and swing. Obviously, the loading phase in lunge and stance phase in walking produces larger moments and forces. Thus, the biomechanical analysis was focused on the loading and stance phases only. The order of walking and lateral lunge was randomized (Fig. 1).

Note: The upper view: a loading phase: bend knee laterally and descend trunk as low as possible to apply maximum loading in the right side; the lower view: a recovery phase: ascend the body and move the center of mass to the left side (Fig. 2).

Fig. 2.

Walking on force platforms and stick figures in Vicon Nexus interface. Note: The instants of heel strike (upper view) and toe off (below view) during walking.

Data processing

A lateral lunge was segmented into descending and ascending phases based on the marker trajectory with the defined events, and gait cycles were defined by heel-strike and toe-off events. The kinematics and kinetics in the lower limb joints were calculated using Plug-in-Gait model. Kinematic and kinetic analysis was done in the sagittal, coronal and transverse planes. The parameters included joint angles, moments and forces in the ankle, knee and hip. The number of subjects was 10 and each had three good trails selected from lunge and walking, respectively. Therefore, 33 paired trials for lunging or walking were finally analyzed. The marker data were filtered using ‘filtfilt’ function from Matlab® with the frequencies between 0.1 and 6 Hz passed. For each trial, the key values like maximum, minimum, range and mean were calculated. All data processing was completed using an in-house program made in Matlab® (2025a). The in-house program has been used in the laboratory for many years and involved in many publications [15,16].

Statistics

The statistical software of SPSS (SPSS v29, IBM, Armonk, NY, USA) was employed. Two sets of data, i.e. walking and lunge, were compared using a general linear model with repeated measures as within-subject, with statistical significance established at p < 0.05, and Bonferroni-adjusted pairwise comparisons for post-hoc tests. This method allows users to input repeated measurements from each subject into the model for one run, and thus has been widely used [15–17]. There were 33 trials of walking and 33 trials of lunging in this study and all trails were compared directly. If p is close to 0.05 and data distribution is not normal, a nonparametric test, e.g. Wilcoxon rank-signed, was used to check p values.

A posterior power analysis was done to checked sample size. Using knee cornal moment as a major variable in this study, the standard deviations were 96 and 49 (Nmm/kg) from two groups respectively and σ the combined standard deviation is estimated 76.2, and the difference of two means is 210 (Table 2). If clinical difference δ is assumed as 150 and given that 2α = 0.01, 1 − β = 0.8 (power), the sample size is estimated as 7 using the method from Ref. [18]. Therefore, the sample size n = 10 used in this study was appropriate.

Results

Participants

Ten participants joined the experiment. They had age as 27 ± 2.7 year-old ranged between 24 and 34 years, body mass 70.86 ± 7.56 ranged 58–82 kg, height 1.67 ± 0.78 ranged 1.54–1.78, and 5 females and 5 males. All were recruited from university campus by using the poster.

Gait parameters

From 33 walking trails used, the mean of walking speeds was 1.13 m/s (standard deviation 0.15 m/s) with minimum 0.85 to maximum 1.53. The mean of cadences was 110.29 step/min (S.D. 9.91) with minimum 93.02 to maximum 137.93. The mean of stride lengths was 1.23 m (S.D. 0.11) with minimum 0.9 to maximum 1.37 m. The mean of stance phases was 54.32% (S.D. 3.77%).

Joint angles

The results showed that (1) ankle angles had larger dorsiflexion, abduction/adduction and transverse rotations in lunge than in walking; (2) knee angles were larger in almost all directions in lunge than walking; (3) hip angles had significantly larger flexion and extension, abduction, and external rotations in lunge than in walking; and (4) pelvic title angles were significantly higher in lunge than in walking, partially reported in Table 1.

Table 1.

The joint angles on lunge.

Unit: degree	Mean	Std. error	95% confidence interval		Sig.	Partial eta squared
			Lower bound	Upper bound
Knee angle in flexion and extension: +flexion & −extension
Max
Walk	17.78	0.96	15.83	19.74	<0.001	0.948
Lunge	65.12†	1.95	61.13	69.10
Min
Walk	2.83	0.91	0.97	4.68	0.387	0.026
Lunge	6.92	4.54	−2.38	16.21
Range
Walk	14.96	0.57	13.80	16.12	<0.001	0.766
Lunge	58.20	4.47	49.06	67.35
Mean
Walk	8.54	0.88	6.74	10.34	<0.001	0.823
Lunge	41.80	2.61	36.46	47.14
Knee angle in adduction and abduction: +adduction & −abduction
Max
Walk	4.05	0.95	2.11	5.98	0.952	0.001
Lunge	4.50	7.37	−10.59	19.58
Min
Walk	−7.89	1.20	−10.34	−5.45	<0.001	0.546
Lunge	−34.01†	4.33	−42.85	−25.16
Range
Walk	11.94	0.74	10.42	13.45	<0.001	0.53
Lunge	38.50	4.98	28.31	48.70
Mean
Walk	−0.76	0.89	−2.59	1.06	<0.001	253
Lunge	−18.64	5.57	−30.03	−7.26

Note: † extremely higher in lunge than in walking. Partial eta squared is effect. A general linear model for repeated measures was used. The movement type was as within-subject factor. Correction option was Beefaroni. Similar signs and notes are used in following tables.

Knee force and moment

Table 2 reported knee forces and moments in 3D directions. The results showed that walking had significantly higher knee forces than lunge, except the anterior and lateral directions (Table 2).

Table 2.

Comparison of knee kinetic parameters between lunge and walking.

Variable units: force (N/kg) and moment (Nmm/kg)	Mean	Std. error	95% confidence interval		Sig.	Partial eta squared
			Lower bound	Upper bound
Knee force in anteroposterior: +anterior & −posterior
Max
Walk	3.03	0.18	2.67	3.39	<0.001*	0.352
Lunge	4.07†	0.23	3.60	4.55
Min
Walk	−0.33	0.05	−0.43	−0.23	<0.001*	0.359
Lunge	0.12	0.09	−0.07	0.30
Range
Walk	3.37	0.17	3.01	3.72	0.030*	0.152
Lunge	3.96	0.23	3.49	4.42
Mean
Walk	1.71	0.15	1.41	2.02	0.001*	0.319
Lunge	2.53	0.16	2.22	2.85
Knee force in medial lateral: +medial & −lateral
Max
Walk	0.90	0.19	0.50	1.30	0.075	0.105
Lunge	0.55	0.18	0.18	0.91
Min
Walk	−1.31	0.24	−1.81	−0.82	<0.001*	0.366
Lunge	−2.89†	0.49	−3.89	−1.90
Range
Walk	2.21	0.15	1.90	2.52	0.001*	0.342
Lunge	3.44	0.36	2.71	4.17
Mean
Walk	−0.42	0.23	−0.89	0.05	0.007*	0.223
Lunge	−1.29	0.38	−2.06	−0.51
Knee force in vertical: +tension & −compression
Max
Walk	−1.43	0.21	−1.87	−1.00	0.159	0.067
Lunge	−1.89	0.21	−2.33	−1.45
Min
Walk	−9.76	0.25	−10.27	−9.25	<0.001*	0.856
Lunge	−7.01	0.23	−7.48	−6.55
Range
Walk	8.33	0.31	7.69	8.97	<0.001*	0.695
Lunge	5.12	0.23	4.64	5.59
Mean
Walk	−7.43	0.17	−7.78	−7.09	<0.001*	0.834
Lunge	−5.39	0.18	−5.76	−5.03
Knee moment in sagittal plane: +flexion & −extension
Max
Walk	761.2	91.1	574.9	947.4	0.006*	0.236
Lunge	1087.6†	101.5	880.1	1295.2
Min
Walk	−213.4	64.6	−345.6	−81.2	0.116	0.083
Lunge	−81.5	46.0	−175.6	12.7
Range
Walk	974.5	42.1	888.3	1060.7	0.036*	0.143
Lunge	1169.1	84.1	997.1	1341.1
Mean
Walk	235.8	80.4	71.4	400.2	<0.001*	0.416
Lunge	675.9	78.4	515.6	836.2
Knee moment in front plane: +adduction & −abduction
Max
Walk	469.3	49.6	367.9	570.6	0.014*	0.191
Lunge	714.6†	107.4	495.1	934.2
Min
Walk	−183.2	36.9	−258.6	−107.8	0.760	0.003
Lunge	−197.9	48.5	−297.1	−98.8
Range
Walk	652.5	40.4	569.8	735.2	0.002*	0.283
Lunge	912.6	80.8	747.4	1077.8
Mean
Walk	171.2	37.9	93.6	248.7	0.089	0.096
Lunge	317.7	90.5	132.5	502.9
Knee moment in transvers plane: +internal & −external
Max
Walk	119.2	11.4	95.8	142.6	0.099	0.091
Lunge	83.6	18.3	46.2	120.9
Min
Walk	−93.2	10.8	−115.3	−71.2	0.051	0.125
Lunge	−50.3	13.5	−78.0	−22.7
Range
Walk	212.4	12.7	186.4	238.4	0.007*	0.223
Lunge	133.9	21.6	89.8	178.0
Mean
Walk	11.5	9.5	−8.0	30.9	0.601	0.01
Lunge	19.6	11.0	−2.9	42.1

Note: † extremely higher in lunge than in walking. Partial eta squared is effect. A general linear model for repeated measures was used. The movement type was as within-subject factor. Correction option was Beefaroni. Similar signs and notes are used in following tables.

*

p < 0.05

Knee flexion and adduction moments were significantly higher in lateral lunge than in walking while knee transverse moment was lower compared to walking (Table 2).

Ankle force and moment

Table 3 reported ankle forces and moments in 3D directions. The results showed that walking had significantly higher ankle forces and moments than lunge (Table 3).

Table 3.

Comparison of ankle kinetic parameters between lunge and walking.

Variable units: force (N/kg) and moment (Nmm/kg)	Mean	Std. error	95% confidence interval		Sig.	Partial eta squared
			Lower bound	Upper bound
Ankle force in vertical: +compression & −tension
Max
Walk	10.25	0.24	9.77	10.74	<0.001*	0.644
Lunge	8.29	0.21	7.86	8.72
Min
Walk	1.87	0.23	1.41	2.34	0.303	0.037
Lunge	2.24	0.22	1.79	2.70
Range
Walk	8.38	0.34	7.69	9.07	<0.001*	0.479
Lunge	6.05	0.28	5.48	6.62
Mean
Walk	7.83	0.16	7.51	8.16	<0.001*	0.724
Lunge	6.34	0.16	6.01	6.68
Ankle force in medial–lateral: +medial & −lateral
Max
Walk	0.86	0.26	0.33	1.39	0.496	0.016
Lunge	0.67	0.16	0.34	1.01
Min
Walk	−1.61	0.26	−2.14	−1.07	0.015*	0.189
Lunge	−2.91†	0.44	−3.82	−2.00
Range
Walk	2.47	0.21	2.04	2.90	0.012*	0.197
Lunge	3.58	0.44	2.69	4.47
Mean
Walk	−0.44	0.18	−0.81	−0.07	0.048*	0.128
Lunge	−1.17	0.31	−1.80	−0.54
Ankle force in anteroposterior: +anterior & −posterior
Max
Walk	2.86	0.32	2.21	3.51	<0.001*	0.373
Lunge	1.94	0.29	1.34	2.54
Min
Walk	−0.32	0.28	−0.89	0.25	0.309	0.036
Lunge	−0.19	0.25	−0.70	0.32
Range
Walk	3.18	0.19	2.79	3.57	<0.001*	0.554
Lunge	2.13	0.18	1.77	2.50
Mean
Walk	1.33	0.36	0.58	2.07	0.091	0.095
Lunge	1.00	0.31	0.37	1.64
Ankle moment in sagittal: +flexion & −extension
Max
Walk	1378.7	55.0	1266.2	1491.3	<0.001*	0.955
Lunge	969.6	45.9	875.8	1063.5
Min
Walk	−98.1	23.6	−146.4	−49.7	<0.001*	0.002
Lunge	106.5	22.2	61.2	151.9
Range
Walk	1476.8	49.8	1374.9	1578.8	<0.001*	0.965
Lunge	863.1	42.4	776.4	949.9
Mean
Walk	635.9	38.7	556.7	715.1	0.010*	0.897
Lunge	559.2	41.3	474.7	643.7
Ankle moment in front: +abduction & −adduction
Max
Walk	182.7	17.9	146.2	219.2	<0.001*	0.825
Lunge	70.9	8.4	53.7	88.1
Min
Walk	−111.8	41.6	−196.9	−26.8	0.581	0.207
Lunge	−103.1	38.0	−180.8	−25.5
Range
Walk	294.5	41.5	209.6	379.5	<0.001*	0.577
Lunge	174.1	35.4	101.6	246.5
Mean
Walk	35.6	23.8	−13.2	84.3	0.005*	0.011
Lunge	−12.3	19.9	−53.0	28.5
Ankle moment in transverse: +internal & −external
Max
Walk	102.5	14.3	73.2	131.7	<0.001*	0.322
Lunge	317.2†	56.8	201.0	433.3
Min
Walk	−148.1	14.3	−177.4	−118.9	0.016*	0.185
Lunge	−68.6	19.8	−109.0	−28.2
Range
Walk	250.6	17.7	214.4	286.9	0.009*	0.214
Lunge	385.8	50.4	282.8	488.8
Mean
Walk	−28.5	11.0	−50.9	−6.1	0.002*	0.291
Lunge	116.8	36.6	41.9	191.7

*

p < 0.05

Hip force and moment

Table 4 reported hip forces and moments in 3D directions. The results showed that walking had significantly higher hip forces than lunge in most of directions except the posterior. Hip moments were significantly higher in walking than in lunge, except in the external rotation direction (Table 4).

Table 4.

Comparison of hip kinetic parameters between lunge and walking.

Variable units: force (N/kg) and moment (Nmm/kg)	Mean	Std. error	95% confidence interval		Sig.	Partial eta squared
			Lower bound	Upper bound
Hip force in anteroposterior: +anterior & −posterior
Max
Walk	2.21	0.07	2.06	2.36	<0.001*	0.901
Lunge	0.42	0.09	0.22	0.61
Min
Walk	−1.46	0.13	−1.73	−1.19	<0.001*	0.377
Lunge	−2.82†	0.30	−3.43	−2.21
Range
Walk	3.67	0.15	3.36	3.99	0.263	0.043
Lunge	3.23	0.35	2.52	3.95
Mean
Walk	0.75	0.06	0.63	0.88	<0.001*	0.885
Lunge	−1.50	0.16	−1.83	−1.16
Hip force at medial–lateral: +medial & −lateral
Max
Walk	1.29	0.15	0.97	1.60	0.075	0.106
Lunge	0.63	0.33	−0.04	1.30
Min
Walk	−1.60	0.14	−1.89	−1.30	0.001*	0.308
Lunge	−2.81†	0.26	−3.35	−2.28
Range
Walk	2.88	0.16	2.57	3.20	0.026*	0.159
Lunge	3.44	0.23	2.97	3.91
Mean
Walk	0.01	0.16	−0.31	0.33	0.002*	0.297
Lunge	−1.19	0.28	−1.76	−0.62
Hip force at vertical: +tension & −compression
Max
Walk	−0.52	0.20	−0.92	−0.12	0.033*	0.148
Lunge	−1.11	0.20	−1.52	−0.70
Min
Walk	−9.00	0.24	−9.49	−8.51	<0.001*	0.803
Lunge	−6.73	0.18	−7.11	−6.35
Range
Walk	8.48	0.29	7.89	9.07	<0.001*	0.721
Lunge	5.62	0.19	5.24	6.00
Mean
Walk	−6.66	0.16	−6.98	−6.33	<0.001*	0.806
Lunge	−4.91	0.17	−5.26	−4.56
Hip moment in sagittal: +flexion & −extension
Max
Walk	356.7	53.6	247.2	466.3	0.953	0.001
Lunge	351.9	89.9	168.0	535.9
Min
Walk	−1204.5	90.1	−1388.9	−1020.2	<0.001*	0.765
Lunge	−412.7	43.9	−502.4	−322.9
Range
Walk	1561.3	70.8	1416.5	1706.1	<0.001*	0.635
Lunge	764.6	79.3	602.3	926.9
Mean
Walk	−644.6	87.3	−823.1	−466.2	<0.001*	0.616
Lunge	−55.6	74.4	−207.8	96.5
Hip moment in front plane: +adduction & −abduction
Max
Walk	585.3	77.2	427.4	743.1	0.009*	0.215
Lunge	369.1	44.2	278.7	459.6
Min
Walk	−491.4	56.4	−606.8	−376.1	0.010*	0.205
Lunge	−262.0	59.0	−382.8	−141.3
Range
Walk	1076.7	55.3	963.6	1189.8	<0.001*	0.515
Lunge	631.2	58.6	511.4	750.9
Mean
Walk	73.7	84.7	−99.5	246.8	0.615	0.009
Lunge	32.1	43.4	−56.7	120.8
Hip moment in transverse: +internal & −external
Max
Walk	95.7	13.4	68.3	123.1	<0.001*	0.416
Lunge	20.3	8.6	2.7	38.0
Min
Walk	−173.4	13.5	−200.9	−145.8	<0.001*	0.683
Lunge	−409.4	26.4	−463.4	−355.4
Range
Walk	269.1	13.7	241.1	297.0	<0.001*	0.521
Lunge	429.7	21.7	385.3	474.1
Mean
vWalk	−16.3	10.2	−37.1	4.6	<0.001*	0.755
Lunge	−198.1	16.8	−232.4	−163.8

*

p < 0.05

Discussion

Major findings

In the knee, the lateral lunge produced higher abduction moment by roughly 34% and lateral force by roughly 54% than walking. Knee flexion and adduction moments were significantly higher in lateral lunge than in walking while knee transverse moment was lower compared to walking. In the ankle, the joint force in the medial–lateral was significantly greater in lunge than in walking but less in other directions. In the hip, lateral lunge had significantly higher forces than walking in the posterior direction, but hip moments were significantly higher in walking than in lunge, except in the external rotation direction. Most of the joint angles were significantly larger in lateral lunge than in walking.

Comparison with previous studies

The previous studies on forward lunge have shown greater change in knee moment, while this study also observed the differences in knee moment when lateral lunge is performed, the greater knee moment is found [2,18,19]. In other studies, the forward lunge has the higher knee moment, knee angle, hip moment, because the biomechanical position of the subject allows the maximum parameters [10,12,20]. Compared with lateral lunge, forward lunges have more mechanical advantages and more qualitative kinetic and kinematic outputs. The studies on backward lunge have shown more power and energy consumed, as the posture at this position is challenging to sustain [9]. The past studies with the general kinetics and kinematics of walking are similar to our study [20,21]. As there is little research on lateral lunge, it is difficult to directly compare our results with the previous ones numerically.

Limitation

There were a few limitations. The first point is the small sample size of participants. More diverse participants may have enhanced the findings of this study. Secondly, a single force platform was used for the loading side in this study; if two platforms were used, the other side would have been studied. Thirdly, if muscle activity, i.e. electromyography (EMG), had been added into the study, it would have given more useful information on this topic [21].

Future studies

The study could be conducted in clinical conditions, for example osteoarthritis and post-operative knee surgeries. If the patients were recruited, the results could have been useful for the clinicians. In addition, it would be useful if this lateral lunge were compared with other conventional knee rehabilitation programs.

The study could be conducted on the back pain conditions, as previous studies showed that deep lunge has effect on back pain, and thus it would be worth exploring if lateral lunge would have effect on back pain in future.

A comparison of muscle activities using EMG between lateral lunge and normal walking would be an interesting project.

Clinical relevance

This study provides a basic reference to clinicians who prescribe rehabilitation programs for patients. As most biomechanical parameters in lateral lunge were less than walking, it is considered that lateral lunge is suitable for the patients who need to improve the abductive or adductive muscles. Given the fact that the outcomes from this study were from static or semi-static experimental conditions, the related rehabilitation program should not consider quick or dynamic lateral lunge. In addition, for young adults who are frequently exposed to lateral loading during sport activities, the results from this study may not be suitable for them and thus further experiment should be designed to strengthen the translational relevance of the findings.

Conclusion

The purpose of the study was to compare the kinematics and kinetics of the lower limb joints between lateral lunge and walking. It is found that the joint angles were significantly larger in lunge than in walking; knee force was significantly higher in the lateral roughly by 50% and knee moments were significantly higher in the adduction by roughly 30% in lunge than in walking; hip moment was significantly higher in the external rotation direction by roughly 53% in lunge than in walking. Most of other parameters were less in lateral lunge than in walking. Considering all the findings, lateral lunge could be used as part of a rehabilitation program for any clinical issue pertaining to the knee.

Authorship

All authors made substantial contributions to the article.

Use of artificial intelligence

None declared.

Funding

None declared.

Ethical considerations

The School of Medicine Research Ethics Committee approved this study as approval No. UOD-SMED-SLS-TPG-20024-24-09.

Informed consent

Every participant signed the written consent form.

Conflict of interests

None declared.

Acknowledgements

The authors would like to thank you to Mr. Sadiq Nasir and Mr. Alan Duncan for their help with data collection and are grateful to all voluntary participants for joining in the study.