Efficiency examination of a 6-month trunk prevention program among recruitment kayak-canoe athletes: A randomized control trial

Abstract

BACKGROUND:

Trunk prevention training, which provides the basis of several conditioning training programs, is used in sports at professional and amateur levels, taking the specifications of the given sport and the age-related characteristics of the athletes into consideration.

OBJECTIVE:

Our aim was to examine the strength and flexibility of muscles responsible for correct posture, the lumbar motor control ability and the posture of recruitment kayak-canoe athletes.

METHODS:

Controlled, randomized examination with 103 persons (age: 15.1 $\pm$ 3.5 years), who were divided into two groups. Fifty were in the intervention group, who took part in the 6-month trunk prevention training program (height: 162.30 cm, body weight: 49.70 $\pm$ 10.32 kg), 53 in the control group (not performing trunk prevention training) (height: 158.24 cm, body weight: 51.45 $\pm$ 11.71 kg). The strength of core muscles was measured with Kraus-Weber test, muscle flexibility with Kempf-test, lumbar motor control ability with Sitting Forward Lean and Leg Lowering test and posture with photogrammetry test before and after the program.

RESULTS:

Static strength of abdominal muscles ( $p<$ 0.001), superficial and deep dorsal muscles ( $p<$ 0.001), flexibility of knee extensors ( $p<$ 0.001), chest muscles ( $p<$ 0.001), the lumbar motor control ability ( $p<$ 0.001) and habitual posture ( $p<$ 0.001) significantly improved in the intervention group. The post-measurements in the intervention group were significantly ( $p<$ 0.001) better than in the control group.

CONCLUSIONS:

As a result of the trunk prevention training the strength of core stabilization muscles, the lumbar motor control ability and the posture also improved in case of recruitment athletes.

Keywords

Trunk prevention training sports physiotherapy lumbar motor control kayak-canoe recruitment

1. Introduction

The special feature of kayak-canoe sport is the sense of balance due to water resistance, the weight of the boat and body weight. As every movement starts from the trunk, the trunk acts as a dynamic stabilizer, it gets the central role in the effort [1]. Development of controlled trunk motion and dynamic stabilization can not generally be used (in the usual form) among these athletes for the greater sense of balance. The main exercise groups are defined as the dynamic stabilization exercise program, but not standardized [1]. Due to asymmetric movements and high center of gravity, trunk movements insuring stability are much more frequent. Beside unilateralism and rotation, there are significant flexion and extension motions in the trunk [1]. Due to frequent trunk movements and weak core muscles, the core muscles can injure and lead to back pain [1, 2]. In case of athletes the connection between weak core muscles and low back pain develops at a young age [3].

The intensity of the load is exaggerated in competitive sports [1]. In the recruitment age group prevention has an important role in the later sport career [1]. Trunk prevention training can play a role in the primary and secondary prevention of non-specific low back pain and the sports injuries of the spine, limbs and other sports injuries through the strengthening of core muscles, the appropriate motor control and the improvement of balance [4, 5, 6, 7, 8, 9, 10].

Parts of the trunk prevention program are the posture, the muscle balance and lumbar motor control [16].

One of the primary effects of the training is that as a result there of the static strength of core muscles, core stability, static and dynamic balance, and the relative strength of the lower and upper limbs also improves [17, 18, 19, 20, 21, 22, 23, 24].

In case of sports where the specific movements involve balancing to a great extent, or the movements are carried out on unstable surfaces, e.g. on boats, the athletes possess a significantly better balancing ability, which must be taken into consideration in the trunk prevention training [17, 25, 26].

The novelty of this research is that we developed a trunk prevention exercise program that takes into account the age and physiological characteristics of the recruitment age group, helps to learn the basis of core training among adults, and takes into account the specific features of the sport, exercising in boat, on instable surface. In addition, we evolved a complex trunk statement examining system for recruitment (age group) athletes, that tests the balance of the muscles responsible for posture, habitual posture and lumbar motor control.

Our aim was to examine the strength and flexibility of core muscles, the lumbar motor control ability and posture of recruitment kayak-canoe athletes. A further aim was to develop a trunk prevention training program appropriate for the recruitment age group and for the given sport. Following the trunk prevention training program our aim was to examine the changes in muscle strength and flexibility, lumbar motor control ability and posture.

2. Hypotheses

H1: It is assumed that among recruitment kayak-canoe athletes the strength of stabilizing core muscles is not appropriate despite the regular training.

H2: It is assumed that the flexibility of the muscles necessary for the correct posture is not appropriate in case of the recruitment kayak-canoe athletes.

H3: It is assumed that the lumbar motor control ability is not appropriate in case of the recruitment kayak-canoe athletes.

H4: It is assumed that the habitual posture is not correct in case of the kayak-canoe athletes.

H5: It is assumed that as a result of trunk prevention training, the core muscle strength of recruitment kayakers will increase.

H6: It is assumed that as a result of trunk prevention training, the flexibility of core muscles will increase in case of recruitment kayakers.

H7: It is assumed that in case of recruitment kayakers, as a result of trunk prevention training, the lumber motor control ability will improve.

H8: It is assumed that the posture of recruitment kayakers will improve as a result of trunk prevention training.

3. Materials and methods

We conducted a longitudinal randomized controlled examination among the recruitment kayak-canoe athletes of Baranya County. The randomisation process took place before the baseline examination. The survey was carried out before beginning the trunk prevention training program and was repeated 6 months later. The intervention group took part in a 6-month trunk prevention training in addition to the usual training program. The control group only participated in the usual training program.

Table 1
Description of the examined sample

	Total		Intervention group		Control group
	$n=$ 103		$n=$ 50		$n=$ 53
	Mean/frequency	SD	Mean/frequency	SD	Mean/frequency	SD	Z/ $\chi^{2}$		$p$
Age	15.39	3.83	15.22	3.70	15.55	3.97	$-$ 0.	59	0.553
Gender (male/female)	76/27		37/13		39/14		0.	002	0.962
BMI (kg/m ${}^{2}$ )	19.73	2.77	18.87	3.25	20.54	1.91	$-$ 3.	651	$<$ 0.001
Body fat (%)	17.97	5.28	17.52	6.05	18.40	4.44	$-$ 1.	232	0.218
Muscle mass (%)	35.73	3.56	35.45	4.76	35.99	1.82	$-$ 1.	883	0.060
Kayak/canoe	92/11		45/5		47/6		0.	047	0.828
Number of years in sport	3.56	2.65	3.72	3.00	3.42	2.29	$-$ 0.	067	0.947
Number of trainings per week	6.06	1.25	6.36	1.39	5.77	1.03	$-$ 2.	881	0.004
Length of training (h)	2.00	0.00	2.00	0.00	2.00	0.00	–		–
Have they had sports injury (Yes/No)	10/93		4/46		6/47		0.	324	0.569

Figure 1.

Consort flow diagram of criteria in the study.

3.1 Materials (patients)

The consort flow diagram shows the enrolment (Fig. 1). A total of 103 persons were involved in the research. The mean age of the intervention group ( $n=$ 50) was 16.13 $\pm$ 3.5 years, the proportion of the genders was 34 (68%) males and 16 (32%) females. The mean age of the control group ( $n=$ 53) was 15.87 $\pm$ 3.7 years, and concerning the proportion of the genders, 38 persons (72%) were male and 15 (28%) female.

Inclusion criteria: over 10-year-old, recruitment-age athletes could participate in the survey who take part in 5 trainings weekly in the competitive kayak-canoe sport, and have been kayaking for a minimum of one year.

Exclusion criteria: operation and sports injury in the last three months, participation in trunk prevention therapy in the last six months.

The examinations were conducted in the gymnasium of the Pécs Kayak-Canoe Club, at the Institute of Physiotherapy and Sports Sciences of the Faculty of Health Sciences of the University of Pécs, and at the Orfű water training site of the Pécs Kayak-Canoe Club (Table 1).

Table 2
Kraus-Weber test

Test description

Evaluation

Figure

K-W. 1.: Examination of the static strength of abdominal muscles m. obliqus internus-, externus abdominis, m. rectus abdominis, m. transversus abdominis

The subjects lie flat on their back, with hands behind the neck and lift their extended legs at a 30-degree angle with the flat plane, holding the position for 10 seconds.

10 points if the position is held for 10 seconds. If the lower back is lifted off the floor, no points are given.

K-W. 2.: Examination of the strength of abdominal muscles m. obliqus internus-, externus abdominis, m. rectus abdominis, m. transversus abdominis

The subjects lie flat on their back, with hands behind the neck, and perform a sit-up while their legs are held down by the examiner.

A complete sit-up: 10 points, and 5 points for a partially successful sit-up.

K-W. 3. Examination of the strength of abdominal muscles m. obliqus internus-, externus abdominis, m. rectus abdominis, m. transversus abdominis

The exercise is similar to the previous one, but now it is performed with bent knees, and evaluated in the same way.

A complete sit-up: 10 points, and 5 points for a partially successful sit-up.

K-W. 4.: Examination of superficial dorsal muscles m. transversospinalis, m. erector spinae, m. spinalis, m. gluteus maximus et medius, m. quadriceps, m. triceps surae, m. popliteus, m. peroneus longus et brevis

The subjects lie on their stomach with a soft support under their lower abdomen, with their hands behind the neck, and their legs extended, and they lift their trunk up and hold the position for 10 seconds.

Holding the position for 10 seconds: 10 points. If the subject holds the position for a shorter time, one point is awarded for each second the position is held for.

K-W. 5.: Examination of the static strength of deep dorsal muscles m. transversospinalis, m. erector spinae, m. spinalis, m. gluteus maximus et medius

The subjects lie on their stomach, and lifts their extended legs and hold the position for 10 seconds.

Holding the position for 10 seconds: 10 points. If the subject holds the position for a shorter time, one point is awarded for each second the position is held for.

K-W. 6.: Examination of the flexibility of knee flexors m. biceps femoris, m. semitendinosus, m. semimembranosus, m. triceps surae

The subjects stand erect and perform a trunk flexion forward and touch the ground while their knees remain extended.

If the subject touches the floor: 10 points. If they do not reach the floor then the distance between the floor and the tip of the subject’s fingers is measure and one point is deducted for every 2.5 cm.

K-W: Kraus-Weber test, K-W. 1.: the static strength of abdominal muscles, K-W. 2. and 3: the muscle strength of abdominal muscles, K-W. 4.: the static strength of superficial dorsal muscles, K-W. 5.: the static strength of deep dorsal muscles, K-W. 6.: the flexibility of knee flexors.

3.2 Methods

The exercises of the Kraus-Weber and Kempf tests were applied to examine the strength of core muscles and for the testing of the muscle strength and muscle flexibility necessary for the biomechanically appropriate posture [27, 28, 29, 30]. The Sitting Forward Lean (SFL) test and Leg Lowering (LL) test were used for core muscle stabilization and for examining the lumbar motor control ability [31, 32]. The examination of posture was carried out with a photogrammetry test (Postural Analysis Gird Chart) [33, 34].

Table 3
The examination of muscle flexibility (according to Kempf)

Test description

Evaluation

MF1A.: Examination of the flexibility of

m. pectoralis major (Kempf 7)

The subjects lie on their side, the lower leg is extended, the upper leg is bent at a right angle and the knee is placed on the floor. One hand touches the opposite knee. The extended upper limb is then pulled back diagonally.

Good

=

If the hand touches the floor while the arm is extended Needs stretching

=

If the hand does not touch the floor, and the distance between the floor and the third finger is measured with a tape measure

MF2L: Examination of the flexibility of

m. quadriceps femoris (Kempf 8)

The subjects stand in front of a chair with their back to it, with straight trunk and the head is a continuation of the trunk, arms extended next to the trunk, one leg is extended, the other is bent and placed on the chair. The heel is pulled by the therapist towards the ischial tuberosity.

Good

=

If the heel touches the ischium Needs stretching

=

If the heel does not reach the ischial tuberosity

MF: muscle flexibility, 1: Kempf 7, A: arm, 2: Kempf 8, L: leg.

3.2.1 Kraus-Weber test

The test consists of six exercises, 0–10 points could be given for each exercise, each of which was scored separately, and also evaluated on the basis of the total number of points (0–60). The maximum total of points was 60, between 50–60 points the condition of core muscles is considered very good, between 50–40 it is good, and between 0–40 it is considered weak [27] (Table 2).

3.2.2 Kempf test

The test system created by Hans-Dieter Kempf is perfectly suitable for the examination of the strength and flexibility of core muscles, and is regularly applied throughout Central and Eastern Europe for preventive, rehabilitation and occupational therapy purposes among athletes, patients and ordinary people as well. The test consists of eight exercises concerning muscle strength and flexibility, however, in our study we only used the exercises aimed at the examination of the flexibility of the m. pectoralis major (Kempf 7), and the m. quadriceps femoris (Kempf 8) [28, 29, 30] (Table 3).

3.2.3 Sitting forward lean (SFL) test

Test description: The subjects sit, feet resting on the ground, the lumbar section is in neutral position. The 0 point is marked at the level of the sacral 1 vertebra, and from here 10 cm is measured up towards the cranial. Then a 120-degree, maximum hip flexion is requested, repeated 5 times. After performing the exercise the subject is asked to take exactly the same sitting position as before, and the distance between the two points (0–10 cm) is measured with a tape measure. Evaluation: The difference between the values was observed and given in mm. The received value was considered normal if it was 10 cm after performing the exercises, a 3 mm deviation in either direction (from 10.4 cm and 9.6 cm) indicates inappropriate lumbar motor control ability [31] (Fig. 2).

Figure 2.

Lumbar motor control tests.

Table 4

Examination of habitual posture

Test description

Evaluation

Front view: front-view median, shoulder-pelvis symmetry, trunk-arms triangle.

The parameters determining the posture were defined through points. In frontal plane, if the lines of the shoulders and the pelvis are parallel: 1 point, if asymmetrical: 2 points. If the frontal median runs through the line of the nose and the navel, and touches the floor in the middle between the two feet: 1 point in case of a physiological frontal median, if it does not touch these points, in case of a non-physiological median, 2 points were given.

Side view: side-view median, cervical, thoracic, lumbar curve.

In the sagittal plane, if the curves of the spine were of physiological scale, 1 point was given, if they were non-physiological, 2 points were given. In the sagittal plane the median must touch the ear, the lumbar 1 and 5 vertebrae and finally reach the ground in the line of the malleolus lateralis, this was 1 point. If the median did not touch one of these points, 2 points were given.

3.2.4 Leg lowering (LL) test

Test description: The subjects are in supine, the hip is flexed in 90 degrees, the knee is fully flexed, the lumbar section is in neutral position.

A BPU (Biopressure Unit) pressure sensor is placed under the lumbar section. The BPU must be inflated to 40 mmHg and the lumbar section must be pressed down to a 45 mmHg value on the BPU. The leg must be lowered 5 times, after each other. The changes in pressure while performing the exercise is given in mmHg. The deviation from 45 mmHg within $\pm$ 5 mmHg is considered adequate lumbar motor control ability, a higher scale of deviation means inadequate lumbar motor control ability [32] (Fig. 2).

3.2.5 Posture test

The habitual posture was examined with a photogrammetry (Postural Analysis Gird Chart) test. In the frontal plane the front-view median, the pelvis-shoulder symmetry and the arm-trunk triangle was examined. In the sagittal plane the side-view median, the cervical-trochal-lumbar curve [33, 34] (Table 4).

Table 5
The kayak-canoe training

Month	Purpose/techniques	Exercise program
1	Basic endurance, technique development	Warm up: Without terrestrial warm up, with the use of sport specific exercises (kayak or canoe), 2 km rowing, duration: 12–14’ depending on the age group and efficiency Main period: 60’ easy pace rowing, taking care of the precise execution of the technique Cool down: 10’ terrestrial gymnastics, stretching
2	Swimming training	Warm up: 500 m swimming, in easy pace, with technical exercises Main period: 4 $\times$ 400 m rapid swimming; 1’ rest period, intensity: 60–70% pace Cool down: 2–300 m individual breast- and backstroke
3	Strength development, weight training	Warm up: 5’ jogging run in the gym, 10’ gymnastic exercises used during running Main part: Circuit training: 15 equipment, 20” workout per equipment, 15” rest period between the equipments, 4 sets, 2’ rest period between the sets, resistance: 50% of maximum resistance, intensity: 70%, all the muscle groups are exercised Cool down: 5’ jogging; 10’ gymnastics; 10’ static stretching
4	Strength development with weight training, muscle group specific training, maximal muscle strength increasing	Warm up: 5’ jogging run in the gym, 10’ gymnastic exercises used during running Main period: chest press with maximum 80% resistance, 6 $\times$ 4 rest period: 2–3’; chest fly with cables with 80% of the intensity, 6 $\times$ 8 rest period: 2’; chest press with 1 kg weight, with 70% resistance, on a bench positioned in 45 ${}^{\circ}$ , 4 $\times$ 8 rest period: 2’; biceps exercise with 1 kg weight, with 70% resistance, in sitting position with changed arms, 5 $\times$ 8 rest period: 1’; biceps exercise on scott bench, 80% resistance with french rod 4 $\times$ 8, rest period: 2’ Cool down: 5’ jogging; 10’ gymnastics; 10’ static stretching
5	(Terrestrial) mountain running	Warm up: 1.5’ km outdoor jogging, 10’ gymnastics Main part: circle runing 2 $\times$ , distance: 6.3 km, interval training Cool down: 15’ gymnastics, stretching
6	(In water) kayak-canoe, adaptation of the acquired physical fitness to the sport specific area	Warm up: 10’ jogging, 10’ gymnastics, 10’ easy pace rowing Main period: partial workout/training, 10 $\times$ 4’ pace rowing, 1’ rest periods, intensity: 70–80% Cool down: 2 km individual rowing with 50–60% of the intensity with technical exercises

Table 6

The applied trunk prevention program

Month	Exercise program (main period)	Intensity/repetition	Rest period	Duration
1	Sensation of correct posture in sitting and standing position Sensation of selective muscle contraction, (m. transverses abdominis, m. multifidus, mm. rhomboideii, middle fibers of trapesius) Cocontraction	30% of maximum strength 10 $\times$ 1–3 sec straining	5 sec between the exercises	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	10 $\times$ 6 sec	5 sec between the exercises	5 minutes
2	Automatization of correct posture in sitting and standing position Isometric exercises on stable surface (m. transverses abdominis, m. multifidus, mm. rhomboideii, middle fibers of trapesius) Cocontraction	30–50% of maximum strength 12 $\times$ 3–10 sec straining	5 sec between the exercises	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	10 $\times$ 10 sec	5 sec between the exercises	5 minutes
3	Static exercises on instable surface Lumbar motor control ability improving exercises in supine, in lateral lying and in hands and knees position	50% of maximum strength 10 $\times$ 10 sec straining	5 sec between the exercises	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	6 $\times$ 16 sec	5 sec between the exercises	5 minutes
4	Dynamic exercises on stable surface, proprioceptive exercises Lumbar motor control ability improving exercises in kneeling and half-kneeling position	30–50% of maximum strength 2 $\times$ 16 repetition	50 sec between the sets	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	6 $\times$ 16 sec	5 sec between the exercises	5 minutes
5	Dynamic exercises on instable surface proprioceptive exercises Lumbar motor control ability improving exercises in sitting position	30–50% of maximum strength 3 $\times$ 14 repetition	5 sec between the exercises	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	6 $\times$ 16 sec	5 sec	5 minutes
6	Resistance exercises with dynamic motions on instable surface, sport-specific exercises Lumbar motor control ability improving exercises in standing position	30–50% of maximum strength 3 $\times$ 14 repetition	50 sec	15 minutes
	Hip flexor, knee extensor and m. pectoralis major stretching	6 $\times$ 16 sec	5 sec	5 minutes

3.2.6 The applied exercise program

The kayak-canoe training program (Table 5)

The trunk prevention training happend in the preseason, in autumn and winter. There were training 8 times per week, that took 1–1.5 hours per occasion. In this season 1 minute rest period was for 3–5 minute load, compared to a 60–70% intensity.

The applied trunk prevention exercise program (Table 6)

The trunk prevention training was 5 times per week, 30 minutes per occasion. The warm up was 5 minutes (circulation increasing exercises), the main period was 20 minutes (Table 6 contains the details), the cool down was 5 minutes (stretching, breathing exercises). The exercises were performed once a week with the instruction of a physiotherapist, three times weekly with a coach and once a week at home independently, with the help of written material compiled by the physiotherapist [21, 35, 36, 37]. The members of the intervention group performed the trunk prevention training in addition to their training. The control group participated in a usual training, the training program was identical.

3.2.7 The applied statistical methods

The distribution of the data received in the survey does not imply normal distribution according to the Kolmogorov Smirnov test, thus we applied the non-parameter Mann-Whitney tests which is not sensitive for normality and suitable for comparing two independent samples. We measured the in group changes with Wilcoxon test. to compare the non continuous data we used McNemar and chi-square tests. The null hypothesis of the test in every case is that the two population can be considered identical from the point of view of the examined variable. If the $p$ -value is lower than 0.05 then the null hypothesis is dismissed. In this case the measured data of the two groups are significantly different.

4. Results

4.1 Muscle strength examination of core muscles

On the basis of the examination prior to the exercise program, in the Kraus-Weber test the total score of the intervention group was 42.62, and that of the control group was 39.28, thus we could state that the core muscle strength of the examined athletes is not appropriate, which means that our first hypothesis (H1) was confirmed.

After the therapy, the total score of the intervention group received for the subtasks was 58.34, which indicates that their core muscle strength significantly ( $p<$ 0.001) improved after the therapy. However, the results of the control group only improved by a few tenths (39.77), thus no significant ( $p=$ 0.160) improvement was experienced in their case. In view of the above, our 5 ${}^{\text{th}}$ hypothesis (H5) was confirmed as well.

When comparing the results of the two groups after 6 months, it could be observed that the results of the intervention group were significantly better ( $p<$ 0.001) than those of the control group (Table 7).

4.2 Muscle flexibility (MF)

After the trunk prevention exercise program, the muscle flexibility of the left and right m. pectoralis major in the intervention group improved significantly ( $p<$ 0.001), in the control group it is changed, but not significantly ( $p_{\text{left}}=$ 0.157, $p_{\text{right}}=$ 0.180).

Table 7
The results of the Kraus-Weber test

The results of the intervention and control group based on the
total score received on Kraus-Weber test before (month 1) and
after the therapy (month 6)
	Mean (points)	SD	Mean rank	$z$	$p$
KWI 1.	42.62	8.31	24.00	$-$ 5.98	$<$ 0.001
KWI 6.	58.34	4.09
KWC 1.	39.28	8.01	1.50	$-$ 1.41	0.160
KWC 6.	39.77	8.19
KWI 6.	58.41	4.06	76.07	$-$ 8.30	$<$ 0.001
KWC 6.	39.34	8.06	29.29

KW: Kraus-Weber test, I: intervention group, C: control group, 1.: month 1, 6.: month 6.

In terms of the muscle flexibility of m. quadriceps femoris, in case of the intervention group, the distance of the heel and the ischial tuberosity on the left and right leg significantly ( $p<$ 0.001) decreased, in case of the control group on the left the changed was not significant ( $p=$ 0.058), on the right leg it was significant ( $p=$ 0.006). In view of the above, our second hypothesis (H2), as well as the 6 ${}^{\text{th}}$ hypothesis (H6) were confirmed.

Comparing the results of the two groups after the program, the results of the intervention group were significantly better ( $p<$ 0.001) than those of the control group (Table 8).

Table 8

The results of muscle flexibility (MF) in the intervention and control group

Kempf 7 left arm
	Intervention group					Control group
	Mean (cm)	SD	Mean rank	$z$	$p$ -value	Mean (cm)	SD	Mean rank	$z$	$p$ -value
MF1 LA 1	65.01	25.10	15.50	$-$ 4.814	$<$ 0.001	70.03	24.03	8.00	$-$ 3.461	0.157
MF1 LA 6	60.05	23.14	20.50	$-$ 5.521		70.05	24.07	8.00
Kempf 7 right arm
MF1 RA 1	65.1	24.1	20.50	$-$ 5.609	$<$ 0.001	70.03	24.05	10.00	$-$ 3.947	0.180
MF1 RA 6	60.03	23.07	25.46	$-$ 5.997		70.07	24.10	10.00
Kempf 8 left leg
MF2 LL 1	20.07	7.10	24.50	$-$ 4.693	$<$ 0.001	19.09	7.09	11.00	$-$ 3.649	0.058
MF2 LL 6	16.05	5.09	14.50	$-$ 5.137		19.05	7.10	11.00
Kempf 8 right leg
MF2 RL 1	18.12	7.17	14.50	$-$ 5.333	$<$ 0.001	18.05	7.11	13.00	$-$ 4.483	0.006
MF2 RL 6	16.09	6.16	17.50	$-$ 6.049		18.03	7.05	13.00

Kempf 7: m. pectoralis major muscle flexibility, Kempf 8: m. quadriceps femoris flexibility, MF: muscle flexibility, L: left, R: right, A: arm, L: leg, 1.: month 1, 6.: month 6.

4.3 The results of lumbar motor control (LMC) tests

4.3.1 LMC I: Sitting forward lean (SFL)

Following the therapy, significant improvement could be observed ( $p<$ 0.001) in the intervention group. No significant ( $p=$ 0.290) improvement was experienced in case of the control group. After the 6-month therapy the values of the intervention group significantly improved ( $p<$ 0.001) compared to those of the control group. In the view of the results, our third hypothesis (H3) and 7th hypothesis (H7) were confirmed (Table 9).

Table 9
The results of the Sitting Forward Lean (SFL) test

The results of the Sitting Forward Lean test in the intervention
and control groups before (month 1) and following the therapy
(month 6)
	Mean (cm)	SD	Mean rank	$z$	$p$ -value
SFL I 1.	2.66	0.84	25.50	$-$ 6.372	$<$ 0.001
SFL I 6.	0.96	0.75
SFL C 1.	3.15	0.81	1.50	$-$ 1.414	0.290
SFL C 6.	3.11	0.82
SFL I 6.	0.96	0.75	27.29	$-$ 8.388	$<$ 0.001
SFL C 6.	3.11	0.82	75.31

SFL: Sitting Forward Lean, I: intervention group, C: control group, 1.: month 1, 6.: month 6.

4.3.2 LMC II: Leg lowering (LL)

After the therapy, a significant improvement was observed in the intervention group ( $p=$ 0.001), and no significant ( $p=$ 0.450) changes were experienced in case of the control group. After the 6-month therapy the values of the intervention group significantly ( $p<$ 0.001) improved compared to the control group. In the view of the results, our third hypothesis (H3), as well as the 7th hypothesis (H7) were confirmed (Table 10).

Table 10
The results of the Leg Lowering (LL) test

The results of the Leg Lowering test in the intervention and
control groups before (month 1) and following the therapy
(month 6)
	Mean	SD	Mean rank	$z$	$p$ -value
LL I 1.	2.56	0.78	25.50	$-$ 6.323	$<$ 0.001
LL I 6.	1.12	0.77
LL C 1.	3.04	0.75	2.00	$-$ 1.732	0.450
LL C 6.	3.05	0.73
LL I 6.	1.12	0.77	27.86	$-$ 2.923	$<$ 0.001
LL C 6.	3.11	0.73	74.77

LL: Leg Lowering, I: intervention group, C: control group, 1.: month 1, 6.: month 6.

4.4 The results of habitual posture

In the habitual posture examination, in case of the frontal plane, the frontal median of the intervention group improved significantly ( $p<$ 0.001), as well as the symmetry of the shoulders ( $p<$ 0.001), and that of the pelvis ( $p<$ 0.001) as a result of the trunk prevention training. In case of the control group there were significant ( $p<$ 0.001) changes in all of the examined parameters. These changes are statistically significant, nevertheless, if we observe the frequency, they do not show clinically significant improvements. Concerning the differences between the two groups, in case of the frontal plane, after the 6 month the results of the intervention group were significantly better in terms of the median ( $p<$ 0.001), and also of the symmetry of the shoulders ( $p<$ 0.001), and of the pelvis ( $p<$ 0.001) (Table 11).

Table 11
The results of the habitual posture in the frontal plane

Habitual posture in the frontal plane
	Intervention group			Control group			Intervention and control group
	Frequency (%)	$\chi 2$	$p$ -value	Frequency (%)	$\chi 2$	$p$ -value	$\chi 2$	$p$ -value
Front. median 1.	13.33	24.04	$<$ 0.001	6.67	19.29	$<$ 0.001	0.74	0.389
Front. median 6.	100.00			10.00			49.09	$<$ 0.001
Shoulder symm. 1.	13.33	24.04	$<$ 0.001	6.67	19.29	$<$ 0.001	0.74	0.389
Shoulder symm. 6.	100.00			10.00			49.09	$<$ 0.001
Pelvis symm. 1.	13.33	24.04	$<$ 0.001	6.67	19.29	$<$ 0.001	0.74	0.389
Pelvis symm. 6.	100.00			10.00			49.09	$<$ 0.001

Front.: frontal, symm.: symmetry, 1.: month 1, 6.: month 6.

In case of the examination of the habitual posture, in the sagittal plane significant improvement was also experienced in the sagittal median ( $p=$ 0.010), in the cervical ( $p<$ 0.001), thoracic ( $p<$ 0.001), and lumbar ( $p<$ 0.001) curve as a result of the trunk prevention training. Significant ( $p<$ 0.001) improvement occurred in all of the parameters in case of the control group. These changes are statistically significant, nevertheless, the frequency shows, that they are clinically not significant improvements. Concerning the differences between the two groups, in case of the sagittal plane, after the program the results of the intervention group were significantly better in terms of the sagittal median ( $p<$ 0.001), and also of the cervical ( $p<$ 0.001), thoracic ( $p<$ 0.001) and lumbar ( $p<$ 0.001) curve. In the view of the results, our 4 ${}^{\text{th}}$ (H4) has been confirmed, as well as our 8 ${}^{\text{th}}$ (H8) hypothesis (Table 12).

Table 12

The results of habitual posture in the sagittal plane

Habitual posture in the sagittal plane
	Intervention group			Control group			Intervention and control group
	Frequency (%)	$\chi 2$	$p$ -value	Frequency (%)	$\chi 2$	$p$ -value	$\chi 2$	$p$ -value
Sag. median 1.	26.67	9.31	0.010	20.00	37.35	$<$ 0.001	0.39	0.825
Sag. median 6.	96.67			23.33			33.67	$<$ 0.001
C. part 1.	43.33	24.04	$<$ 0.001	36.67	26.05	$<$ 0.001	0.28	0.598
C. part 6.	100.00			40.00			25.71	$<$ 0.001
Th. part1.	0.00	27.03	$<$ 0.001	0.00	30.00	$<$ 0.001	1.02	0.313
Th. part 6.	96.67			6.67			48.66	$<$ 0.001
L. part 1.	13.33	24.04	$<$ 0.001	10.00	16.67	$<$ 0.001	0.16	0.688
L. part 6.	100.00			16.67			42.86	$<$ 0.001

Sag.: sagittal, C.: cervical, Th.: thoracic, L.: lumbar, 1.: month 1, 6.: month 6.

5. Discussion

In the examination, a 6-month trunk prevention training was completed among recruitment-age kayak-canoe athletes. We performed core muscle strength and muscle flexibility tests, as well as lumbar motor control ability tests and posture examination.

Several researches confirm that beside regular sports training, the strength and flexibility of core muscles, the lumbar motor control ability and the posture is not correct [26, 34, 38].

5.1 Muscle balance of the trunk

Tse et al. examined rowers of a mean age of 21 years. They applied an eight-week (2 sessions per week) core training program. They examined the strength and flexibility of core muscles (flexion, extension, lateral flexors). A substantial significant improvement ( $p<$ 0.005) was experienced in the core flexibility parameters, and the strength of the lateral flexor muscle group also improved significantly ( $p<$ 0.005) [17].

Tinto et al. examined 20 synchronised swimmers (mean age: 10 years), applied a 6-month (2 sessions/week) core stabilization, strengthening and TRX training. During the survey McGill test was used and the muscle strength of the obliques and transversus abdominis was examined. Significant improvement was experienced ( $p=$ 0.001) in case of most parameters [26].

Prieske et al. applied neuromuscular and core training in case of young (mean age: 17 years) footballers (39 persons). The training lasted 9 weeks (2–3 sessions/week), as a result of which the muscle strength of the trunk extensors improved significantly ( $p<$ 0.05), the time of 10–20 meter sprint also showed significant improvement ( $p<$ 0.05) as well as the kicking power ( $p<$ 0.001) [39].

We got similar results to international publications. Due to the trunk prevention program the muscle balance of core muscles improved significantly ( $p<$ 0.001).

5.2 Lumbar motor control ability

Tinto et al. examined 20 synchronised swimmers (mean age: 10 years), applied a 6-month (2 sessions/week) core stabilization and strengthening training and TRX training. In the survey, lumbar motor control test was performed by Stabilizer Pressure Biofeedback unit. In case of the intervention group a significant improvement ( $p=$ 0.001) occurred in the lumbar motor control ability [26].

Vica külfi cikk (integrative med) [40].

Roussel et al. examined 32 dancers (ballet and modern dance), and performed a lumbopelvic motor control test with “Standing Bow” (SB) pose test. Pathological lumbopelvic control was detected in 13% of the dancers [38].

Similarly to other researches in the literature, in our research the lumbar motor control ability improved significantly ( $p<$ 0.001) after the trunk prevention exercise program.

5.3 Posture

Kovácsné et al. examined the habitual posture and the posture deemed correct in case of ballet, hip-hop and ballroom dancers. Ninety-two dancers participated in the examination, the habitual posture and the posture deemed correct was measured with photogrammetry test. Significant difference was found concerning the posture deemed correct in frontal view, the ballroom dancers showed significantly better ( $p=$ 0.038) posture than the other two examined groups. In view of the results, it was concluded that neither the habitual posture nor the posture deemed correct corresponded to the biomechanically correct posture [41].

Iunes et al. also performed a photogrammetry test among 24-year-old female ballet dancers. The dancers were compared to a control group of 59 non-dancers of similar age. The measurements were carried out through 3 years, with the aim of examining the changes of the lumbar lordosis. The results indicated that the occurrence of increased lumbar lordosis significantly grew in case of ballet dancers [42, 43].

Following the trunk prevention program, posture improved significantly ( $p<$ 0.001) in our research, similarly to other international researches.

6. Conclusions

The condition of the trunk (strength, muscle flexibility, lumbar motor control ability) and the habitual posture of supplied kayak-canoe athletes is inconvenient despite regular training. The condition of trunk and of habitual posture can be improved with trunk prevention training in accordance with age and type of sport.

Footnotes

Acknowledgments

This work was supported by the GINOP 2.3.2-15-2016-00047 grant in name of Brigitta Szilágyi.

Conflict of interest

None to report.

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Efficiency examination of a 6-month trunk prevention program among recruitment kayak-canoe athletes: A randomized control trial

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Hypotheses

3. Materials and methods

Table 1 Description of the examined sample

Table 2 Kraus-Weber test

Table 3 The examination of muscle flexibility (according to Kempf)

3.2.2 Kempf test

3.2.3 Sitting forward lean (SFL) test

3.2.5 Posture test

Table 5 The kayak-canoe training

The kayak-canoe training program (Table 5)

The applied trunk prevention exercise program (Table 6)

3.2.7 The applied statistical methods

4. Results

4.1 Muscle strength examination of core muscles

4.2 Muscle flexibility (MF)

Table 7 The results of the Kraus-Weber test

4.3.1 LMC I: Sitting forward lean (SFL)

Table 9 The results of the Sitting Forward Lean (SFL) test

Table 10 The results of the Leg Lowering (LL) test

Table 11 The results of the habitual posture in the frontal plane

5.1 Muscle balance of the trunk

5.2 Lumbar motor control ability

5.3 Posture

6. Conclusions

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Description of the examined sample

Table 2
Kraus-Weber test

Table 3
The examination of muscle flexibility (according to Kempf)

Table 5
The kayak-canoe training

Table 7
The results of the Kraus-Weber test

Table 9
The results of the Sitting Forward Lean (SFL) test

Table 10
The results of the Leg Lowering (LL) test

Table 11
The results of the habitual posture in the frontal plane