isokinetic neck-sc1-jf-f SAJSM VOL 17 NO. 1 2005 19 Introduction The incidence of cervical spinal injuries in rugby and other sporting and recreational activities has been well document- ed.1, 3, 5, 15, 18, 19, 21-23 Cervical spinal injuries that occur during organised team sports are well publicised; however, the majority of serious sports-related spinal injuries occur during unsupervised activities.18 The incidence of cervical spine injuries in rugby has brought about many precautionary measures including rule changes, new policies for selecting players, and conditioning principles.24 However, more players are exposed to potential injury situations due to the changing nature of the game. Previously the majority of cervical injuries occurred in the scrum, ruck or maul, involving mainly the forwards.19 Increasingly more cervical injuries now occur in the tackle situation,19 exposing the entire team to increased injury risk. A mismatch of physical size and strength between players, combined with differences in skill levels creates a situation conducive to injuries.10 Research done in Argentine rugby showed that younger players aged between 15 and 21 years were at greater risk of muscle or ligament injuries of the cer- vical column, which could in turn cause more serious dislo- cations and/or spinal cord involvement.3 The following cervical spine injury requirements need to be met before the player can return to participation in collision ORIGINAL RESEARCH ARTICLE Isokinetic neck strength norms for schoolboy rugby forwards D E du Toit (DPhil) P Olivier (MA) L Grenfell (MA) B Eksteen (BA (Hons) Biokinetics) Department of Human Movement Science, Nelson Mandela Metropolitan University, Port Elizabeth CORRESPONDENCE: P Olivier Department of Human Movement Science Nelson Mandela Metropolitan University PO Box 77000 Port Elizabeth 6031 Tel: 041 - 504 2497 Fax: 041 - 504 2770 E-mail: pierre.olivier@nmmu.ac.za Abstract Objective. To generate isokinetic neck strength norms for schoolboy rugby forwards. Design. Two hundred and eight schoolboys (17.21 – 1.03 years, mean – standard error of the mean (SEM), chosen from a population of under-19 first and second XV rugby players, participated in this study. The subjects were assessed anthropometrically and isokinetically according to a set protocol. The isokinetic assessment of neck strength was performed with the use of a specially designed stabil- ising chair and halo. The subjects performed a single max- imal exertion set, consisting of 3 repetitions, through each of the cervical spinal movements in the sagittal and frontal planes. The data were analysed statistically according to positional categories (front-, second-, and back-row for- wards), and were used to generate Stanine tables of nor- mative data concerning the force characteristics of the cervical spine. Results. The front-row forwards produced the largest amounts of force during the measurement of peak torque flexion (PTF = 30.00 – 1.39 Nm) and peak torque exten- sion (PTE = 55.26 – 1.42 Nm). Conversely, the second-row forwards performed the best during the measurement of lat- eral flexion peak torque to the right (PTR = 53.71 – 1.51 Nm) and lateral flexion peak torque to the left (PTL = 52.92 – 1.63 Nm) in the frontal plane. The front-row forwards were the most powerful in all the neck movements mea- sured (power generated at 0.2 seconds during flexion (PowF) = 101.54 – 6.43 W, power generated at 0.2 s dur- ing extension (PowE) = 167.31 – 8.03 W, power generated at 0.2 s during lateral flexion to the right (PowR) = 211.92 – 7.44 W, and power generated at 0.2 s during lateral flex- ion to the left (PowL) = 194.81 – 7.73 W). However, fur- ther analysis of the data revealed that few statistically significant differences (p < 0.01 and p < 0.05) existed between the positional categories for the measured vari- ables of peak torque, power generated at 0.2 of a second, peak torque to body mass ratio and cervical range of motion. Conclusion. It appears that the various positional cate- gories have not undergone the expected neck strength adaptations to meet the unique requirements of each posi- tion. The generation of neck strength normative data allows for the effective and quantified comparison of neck strength variables, enabling more effective injury preven- tion and rehabilitation. isokinetic neck-sc1-jf-f 5/3/05 8:56 AM Page 19 20 SAJSM VOL 17 NO. 1 2005 sports; these include possessing normal strength, painless full range of motion, a stable vertebral column and adequate space for the neurological elements.17 While the external forces acting on the sportsman will not decrease, the player must find ways to withstand these forces in order to prevent injury. Proper conditioning of the neck musculature is a prac- tical method of injury prevention.5-7, 12, 16, 25 Through the course of any contact event the cervical spine is subjected to vari- ous forces, which have the potential to cause serious injury. Fortunately the spine is protected by the energy-absorbing capabilities of the paravertebral musculature and the inter- vertebral discs, which effectively dissipate these forces through controlled spinal motion.26 Neck strengthening can therefore improve the energy-absorption capabilities of the neck musculature, thus increasing protection of the cervical spine. A comparison between neck muscle strength, efficiency and relaxation times in normal subjects and those with neck pain, found that all force values were significantly lower in those with neck pain.2 Several authors11,13,29 have demon- strated that the isometric strength measurement of neck muscles is an objective and practical method of estimating functional improvement in response to rehabilitation. In recent clinical studies9,11,20 intensive strength training of the neck muscles was used as the primary treatment for patients with chronic neck pain. The results of this intervention demonstrated reduced pain intensity and increased neck muscle strength. If cervical conditioning is to be used as an injury preven- tion and rehabilitation tool, then reliable data must be avail- able to ascertain the condition of a player s neck musculature and its ability to prevent injury. Normative data providing information on neck strength characteristics can assist in the identification, prevention, and ultimately the rehabilitation of individuals with poor neck musculature char- acteristics. Similar normative data collected from appropriate population groups (e.g. sedentary and other sporting codes) could be applied in the same fashion. The development of an isokinetic evaluation method assessing spinal movement in the frontal and sagittal planes, allows for reliable and valid measurement of neck strength parameters.6, 7 It has been suggested in the literature that normative data on the strength of the neck musculature in healthy individuals are required for comparative evaluation of patients with neck pain.27 The meaningful application of these isokinetic test results therefore hinges on the availability of normative data from which comparisons and clinical conclusions can be drawn. Methodology Subjects Two hundred and eight subjects with a mean age of 17.21 – 1.03 years were assessed anthropometrically and isokineti- cally to establish normative data values. The subjects were chosen from a population of under-19 first and second XV rugby players. Height and weight were measured prior to the subjects participation in the isokinetic assessment. Isokinetic cervical muscular strength testing Methods and procedures as proposed by du Toit 6 and du Toit, et al. 7 were used to examine the force capabilities of the schoolboy rugby forwards neck musculature. Torque pro- duction was measured through the full range of cervical spinal motion during flexion and extension in the sagittal plane and lateral flexion in the frontal plane (Fig. 1). Prior to beginning the neck-strength evaluations, informed consent was obtained and participants answered a series of questions that screened for any prior or current cervical spinal injuries that may have precluded a subject from par- taking in the study. The evaluation session included a set series of warm-up exercises, viz. active full range of joint motion movements, static stretches, and submaximal isometric contractions. Six submaximal warm-up movements were then performed on the isokinetic dynamometer. After completing the 6 submax- imal repetitions the subject s head was placed in the neutral position and the range of motion of the dynamometer was reset to zero. When the subject was ready the isokinetic test commenced. Isokinetic strength testing was performed at 30…/s. Alignment of the dynamometer s input axis corre- sponded with the vertebral prominence (C7) of the cervical spine. Three repetitions of maximal effort through both flex- ion/extension and lateral flexion to the right and left were recorded and taken as being representative of the neck mus- culature s peak torque capabilities.6, 7 Fig. 1. Top: Movement pattern in the sagittal plane – exten- sion to flexion. Bottom: Movement pattern in the frontal plane – lateral flexion to the right and left sides. isokinetic neck-sc1-jf-f 5/7/05 6:48 AM Page 20 SAJSM VOL 17 NO. 1 2005 21 Cervical range of motion testing Two cervical range of motion (CROM) measurements were taken. The first measurement was taken during the subject s performance of the 3 maximal cervical spinal motions. These CROM measurements were labelled maximal voluntary con- traction range of motion flexion/extension (MVCRFE) and maximal voluntary contraction range of motion lateral flexion (MVCRLF) respectively. These measurements spanned the whole range of motion from full extension to full flexion and from full lateral flexion right to full lateral flexion left. Secondly, these measurements were broken down and rep- resented as separate CROM measurements by taking into consideration the anatomical zero. These measurements were labelled maximal voluntary contraction range of motion extension (MVCRE), -flexion (MVCRF), -lateral flexion right (MVCRR), and -lateral flexion left (MVCRL). Statistical analysis The collected data were analysed and used to create nor- mative data presented in Stanine tables. The Stanine tables consisted of 3 main categories; poor, average and good. Every main category also consisted of 3 subcategories. Stanine tables were generated for various measured and calculated variables, namely: peak torque (PT), power gen- erated at 0.2 of a second (Pow), CROM, and PT ratios. Furthermore, one-way analysis of variance (ANOVA) was performed to detect any statistically significant differences for the measured and calculated variables between the vari- ous positional categories. Hypotheses were tested at the 99% and 95% confidence level. Statistical analyses, with the aid of the Pearson s moment product correlation coefficient, were also performed to investigate if certain variables were correlated. Results and discussion Anthropometrical measurements The anthropometrical data are reflected in Table I according to the forward positional categories (front, second, and back row). The back-row forwards body mass proved to be sig- nificantly less than that of the front (p < 0.01) and second rows (p < 0.05). No significant difference existed between the body masses of the front and second-row forwards. The forwards body masses proved to be significantly positively correlated (p < 0.01) with their height and neck circumfer- ence (NC); however, it was not correlated to their neck length (NL). Height was significantly positively correlated (p < 0.01) with body mass and NL, however no correlation existed between height and NC. As expected, the second row was signifi- cantly taller (p < 0.01) than the front and back rows. The rela- tionship between height and NL may explain why the second row players had significantly longer necks (p < 0.01) than players in the front row. Isokinetic measurements Peak torque No significant differences (p > 0.05) existed between the positional categories for the measurement of peak torque flexion (PTF), peak torque extension (PTE), peak lateral flex- ion torque to the right (PTR), or peak lateral flexion torque to the left (PTL) (Table II). This result, especially concerning the measurement of PTE, seems inconsistent with the function of the front row as well as the forces the front rows are exposed to in the scrum. Greater cervical extension strength was expected among the front-row forwards as this would be indicative of their adaptation to the demands of scrummag- Table I. Descriptive statistics of the schoolboy forwards’ anthropometrical data according to positional categories (N = 208) Height (cm) Weight (kg) NL (cm) NC (cm) Position N Mean SEM Mean SEM Mean SEM Mean SEM Front row 78 174.49* 0.64 85.62* 1.42 15.73* 0.19 39.98* 0.31 Second row 52 184.30* 0.58 81.78 1.26 16.68* 0.23 38.93 0.25 Back row 78 178.76* 0.66 76.61* 0.89 16.21 0.22 38.34* 0.20 Forwards 208 178.54 0.45 81.28 0.75 16.45 0.13 39.09 0.16 * Statistically significant difference (p < 0.01) Statistically significant difference (p < 0.05). NL= neck length , NC = neck circumference, SEM = standard error of the mean. Table II. Descriptive statistics of the schoolboy forwards’ peak torque data according to positional categories (N = 208) Peak torque (Nm) Peak torque lateral flexion (Nm) Flexion (PTF) Extension (PTE) Right (PTR) Left (PTL) Position N Mean SEM Mean SEM Mean SEM Mean SEM Front row 78 30.00 1.39 55.26 1.42 53.37 1.33 51.35 1.27 Second row 52 26.04 1.24 54.69 1.57 53.71 1.51 52.92 1.63 Back row 78 28.24 1.12 53.63 1.32 53.38 1.26 51.64 1.36 Forwards 208 28.35 0.74 54.51 0.83 53.46 0.78 51.85 0.8 isokinetic neck-sc1-jf-f 5/3/05 8:56 AM Page 21 22 SAJSM VOL 17 NO. 1 2005 ing. As expected, PTF values were notably lower than those recorded for PTE; this was due to the relative size of the musculature involved in the force production during the recorded movements. Comparatively, PTR and PTL were very similar due to the bilateral muscular arrangement around the cervical spine. The normative data generated from the collected PT mea- surements are presented in Stanine form in Table III. The maximum and minimum measurements taken for each PT variable by an individual are presented in the best and worst recorded rows. The three main Stanine categories, poor , average , and good , are further subdivided. Peak torque to body mass ratio Descriptive statistics for PT to body mass ratio (PT/BM) are given in Table IV. The back-row forwards had the greatest PT (PTF, PTE, PTR and PTL) to body mass ratios. The back-row forwards proved to have a significantly high- er (p < 0.05) PTF/BM than the second rows. Similarly, the back-row forwards proved to have a significantly higher (p < 0.01) PTL/BM than the front rows. As no statistically signifi- cant differences existed between the positional categories on the measurements of PT (Table II), the significant differ- ences observed for the PT/BM variables can be attributed to variations in body mass among the positional categories. Table I shows that the second-row forwards were signifi- cantly heavier (p < 0.05) than the back rows. Thus the larg- er body masses of the second-row players resulted in a decreased and significantly lower (p < 0.05) PTF/BM than that of the back rows. Similarly, the front rows proved to be significantly heavier (p < 0.01) than the second-row players, resulting in the significantly lower (p < 0.01) PTL/BM average calculated. Thus the observed heavier body masses of the front-row players resulted in the significantly lower (p < 0.01) PTL/BM average calculated. The normative data generated for the PT/BM variable is shown in Table V. As can be seen from this table PT/BM val- ues for PTE, PTR, and PTL approach 100%. The notable dif- ference between the observed values of PTE/BM and PTF/BM is indicative of the variation in muscle mass and arrangement around the cervical spine and consequently the production of PT for the respective movement patterns. Likewise the similarity of the PTR/BM and PTL/BM results can also be attributed to the bilateral arrangement of the neck musculature involved in the respective cervical move- ment patterns. Power generated at 0.2 of a second Descriptive statistics (Table VI) of the power generated at 0.2 of a second (Pow) variable, measured in Watts, revealed that the front-row forwards were best in all movement patterns. However, the numerical advantage translated into only 1 sta- tistically significant difference. Front-row forwards proved to Table IV. Descriptive statistics of the schoolboy forwards’ peak torque to body mass data according to positional categories (N = 208) Peak torque to body mass ratio (%) PTF/BM PTE/BM PTR/BM PTL/BM Position N Mean SEM Mean SEM Mean SEM Mean SEM Front row 78 35.19 0.02 65.11 0.02 63.12 0.02 60.74 0.02 Second row 52 31.62* 0.02 67.25 0.02 65.77 0.02 64.94 0.02 Back row 78 37.09* 0.01 70.20 0.02 69.88 0.02 67.51 0.02 Forwards 208 35.01 0.01 67.55 0.01 66.32 0.01 64.33 0.01 * Statistically significant difference (p < 0.05). Statistically significant difference (p < 0.01) Table V. Stanine table of normative data for peak torque to body mass ratio (N = 208) Peak torque to body mass ratio (%) Extremes and Extension Flexion Right-flexion Left-flexion Stanine categories Worst recorded 32 12 28 20 1. Extremely poor 0 - 44 0 - 17 0 - 44 0 - 38 2. Very poor 45 - 50 18 - 20 45 - 49 39 - 47 3. Poor 51 - 56 21 - 25 50 - 56 48 - 57 4. Below average 57 - 62 26 - 30 57 - 60 58 - 61 5. Average 63 - 70 31 - 36 61 - 69 62 - 66 6. Above average 71 - 76 37 - 41 70 - 77 67 - 74 7. Good 77 - 87 42 - 50 78 - 84 75 - 84 8. Very good 88 - 92 51 - 61 85 - 91 85 - 90 9. Excellent 93 + 62 + 92 + 91 + Best recorded 113 81 103 103 Table III. Stanine table of normative data for peak torque (N = 208) Peak torque (Nm) Extremes and Extension Flexion Right-flexion Left-flexion Stanine categories Worst recorded 28 9 24 14 1. Extremely poor 0 - 32 0 - 12 0 -33 0 - 28 2. Very poor 33 - 39 13 - 15 34 - 41 29 - 37 3. Poor 40 - 44 16 - 19 42 - 45 38 - 43 4. Below average 45 - 50 20 - 25 46 - 49 44 - 49 5. Average 51 - 55 26 - 29 50 - 53 50 - 52 6. Above average 56 - 63 30 - 34 54 - 60 53 - 59 7. Good 64 - 70 35 - 42 61 - 66 60 - 65 8. Very good 71 - 77 43 - 51 67 - 72 66 - 71 9. Excellent 78 + 52 + 73 + 72 + Best recorded 87 72 89 80 isokinetic neck-sc1-jf-f 5/3/05 8:56 AM Page 22 SAJSM VOL 17 NO. 1 2005 23 be significantly more powerful (p < 0.01) than the back-row players on the measurement of flexion power generated at 0.2 of second (PowF). However, it was expected that the front-row players would be significantly stronger (Table II) and more powerful (Table VI) than the other positional cate- gories. This would have been an indication of their adapta- tion to the demands of their position within the tight scrum. The normative data for the power generated at 0.2 of a sec- ond variables are shown in Table VII. The data again show that the measurements made through the extension, lateral flexion right, and lateral flexion left movement patterns are fairly similar. Peak torque ratios The normative data represented in Table VIII show the mus- cle strength ratios of the agonist to antagonist for each spe- cific movement pattern of the cervical spine assessed. As discussed previously, extension strength due to the muscle mass involved in the movement is much greater than that of flexion strength. This table illustrates that low ratios are rated as poor or below average (0 - 39%). This is seen by the opti- mal ratio between PTF and PTE being approximately 49 - 53%. Normative data concerning the ratio of cervical flexion to extension strength in the normal population suggest that a ratio of around 60% is optimal.8 However among rugby for- wards stronger cervical extensors are preferable as they will enable the player to resist the forces experienced in the tight scrum. Conversely, the bilateral symmetry of the muscula- ture producing lateral flexion left and right predicts the opti- mal ratio for PTR to PTL to be 100%. These low ratios (Table VIII) can be attributed, in the case of PTF/PTE, to weak cervical flexors; conversely, too high a ratio (Table VIII) is also interpreted as poor or below average and indicative of weak cervical extensors. This principle is also applied in the reflection of PTR/PTL normative data. Cervical range of motion No statistically significant differences were observed between the positional categories during the measurement of CROM (Table IX). The average MVCRFE during the flex- ion movement pattern was 118.15ß. The mean values were 58.63ß from full extension to neutral (anatomical zero) and 58.91ß from neutral to full flexion. During the extension movement pattern a larger MVCRFE was measured (125.79ß). The mean values were 62.66ß from full flexion to neutral and 64.12ß from neutral to full extension. These val- ues correspond well with other measurements reported in the literature. Buck et al.4 reported values of 66ß – 8ß for flex- ion and 73ß – 9ß for extension in a sample of young males. Lind et al.14 only reported a total average flexion and exten- sion of 68ß – 26ß. Wolfenberger et al.28 established the mean CROM for flexion/extension, with the use of radiography, to be 108… in a sample (N = 39) of 20 - 29-year-old males. Dual inclinometry delivered a value of 101…, and with a bubble Table VI. Descriptive statistics of the schoolboy forwards’ power generated at 0.2 of a second data according to positional categories (N = 208) Power Generated at 0.2 of a second (W) PowF PowE PowR PowL Position N Mean SEM Mean SEM Mean SEM Mean SEM Front row 78 101.54* 6.43 167.31 8.03 211.92 7.44 194.81 7.73 Second row 52 72.40 5.60 161.15 7.01 206.63 8.54 184.42 9.16 Back row 78 69.17* 5.21 150.19 8.24 189.42 8.64 178.08 9.14 Forwards 208 82.12 3.55 156.35 4.66 202.16 4.81 185.94 5.04 *= Statistically significant difference (p < 0.01). Table VII. Stanine table of normative data for power generated at 0.2 of a second (N = 208) Extremes and Stanine Power generated at 0.2 of a second (watts) categories Extension Flexion Right-flexion Left-flexion Worst recorded 19 5 25 23 1. Extremely poor 0 - 25 0 - 10 0 - 70 0 - 50 2. Very poor 26 - 60 11 - 20 71 - 105 51 - 80 3. Poor 61 - 95 21 - 40 106 - 140 81 - 120 4. Below average 96 - 125 41 - 55 141 - 160 121 - 160 5. Average 126 - 160 56 - 80 161 - 220 161 - 205 6. Above average 161 - 205 81 - 115 221 - 250 206 - 230 7. Good 206 - 240 116 - 150 251 - 275 231 - 260 8. Very good 241 - 275 151 - 210 276 - 320 261 - 310 9. Excellent 276 + 211 + 321 + 311 + Best recorded 350 300 360 355 Table VIII. Stanine table of normative data for peak torque ratios (N = 208) Ratio (% actual) Extremes and Flexion - Extension Right - Left Stanine categories Low High Low High Worst recorded 19 100 35 143 1. Extremely poor 0 - 11 95 + 0 - 68 132 + 2. Very poor 12 - 25 81 - 94 69 - 76 124 - 131 3. Poor 26 - 32 74 - 80 77 - 83 117 - 123 4. Below average 33 - 39 67 - 73 84 - 87 113 - 116 5. Average 40 - 43 63 - 66 88 - 92 108 - 112 6. Above average 44 - 48 58 - 62 93 - 95 105 - 107 7. Good 49 - 51 55 - 57 96 - 97 103 - 104 8. Very good 52 - 52 54 - 54 98 - 99 101 - 102 9. Excellent 53 - 53 53 - 53 100 100 Best recorded 53 53 100 100 isokinetic neck-sc1-jf-f 5/3/05 8:56 AM Page 23 goniometer 100… of CROM for flexion/extension was obtained.28 Similar results were observed for the measurement of lat- eral flexion left and right CROM. However, the obtained results were smaller than those seen with the measurement of MVCRFE. The average MVCRLF to the left was 111.39ß, and during lateral flexion to the right an average of 111.75ß was recorded. The mean values were 53.8ß from neutral to full lateral flexion right and 56.14ß (average) from neutral to full lateral flexion to the left. Lind et al.14 reported slightly lower averages for both lateral flexion left and right CROM with a value of 45ß – 14ß. Active CROM for lateral flexion left to right, measured with a goniometer, for a sample (N = 20) of males aged from 11 to 19 years was calculated to be 91.1ß.30 The normative data represented in Stanine format in Tables X and XI show complete CROM measurements through the full range of cervical motion in the sagittal (MVCRFE) and frontal (MVCRLF) planes. The results show that the various positional categories do not appear to have undergone the expected specific neck musculature adapta- tions to meet the unique requirements of each position. This may be due to the lack of education of players and coaches on the importance of proper neck musculature condition for safe participation in rugby. This naturally leads to little time and effort spent by coaches and players on specific condi- tioning of the neck muscles resulting in underdeveloped and weak neck muscles. Furthermore, in conjunction with poor or insufficient conditioning of the neck muscles, players of the age investigated in this study possibly have not yet been exposed to sufficient bouts of cervical spinal exertion in the tight scrum to have undergone the needed adaptations. This is, however, more reason to encourage neck musculature conditioning. Conclusion The generation of normative data pertaining to the force characteristics of the neck musculature can be usefully applied as an injury prevention and rehabilitative tool. By identifying weak musculature in players prior to participation possible injury can be avoided. The usefulness of this method of assessment is not only limited to the sporting indi- vidual; the general population can also benefit from neck musculature conditioning to prevent or rehabilitate the painful cervical spine. REFERENCES 1. Armour KS, Clatworthy BJ, Bean AR, Wells JE, Clarke AM. Spinal injuries in New Zealand rugby and rugby league — a twenty year survey. N Z Med J 1997; 110: 462-5. 2. Barton PM, Hayes KC. Neck flexor muscle strength, efficiency, and relax- ation times in normal subjects and subjects with unilateral neck pain and headache. Arch Phys Med Rehabil 1996; 77: 680-7. 3. Bottini E, Poggi EJT, Luzuriaga F, Secin FP. Incidence and nature of the most common rugby injuries sustained in Argentina (1991 - 1997). Br J Sports Med 2000; 34: 94-7. 24 SAJSM VOL 17 NO. 1 2005 Table X. Stanine table of normative data for cervical range of motion (N = 208) Extremes and Stanine Range of Motion – MVCRFE & MVCRLF (deg) categories Extension Flexion Right-flexion Left-flexion Worst recorded 87 76 70 73 1. Extremely poor 0 - 96 0 - 87 0 - 86 0 - 88 2. Very poor 97 - 103 88 - 97 87 - 94 89 - 94 3. Poor 104 - 111 98 - 104 95 - 103 95 - 102 4. Below average 112 - 119 105 - 114 104 - 107 103 - 108 5. Average 120 - 131 115 - 122 108 - 114 109 - 113 6. 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Descriptive statistics of the schoolboy forwards’ cervical range of motion data according to positional categories (N = 208) Range of motion - MVCRFE & MVCRLF (deg.) Flexion Extension Right – flexion Left - flexion Position N Mean SEM Mean SEM Mean SEM Mean SEM Front row 78 117.19 1.8 123.29 1.74 109.54 1.43 109.46 1.38 Second row 52 120.02 2.48 129.64 2.27 113.62 1.65 113.85 1.69 Back row 78 117.86 1.99 126.04 1.85 112.71 1.29 111.68 1.33 Forwards 208 118.15 1.18 125.76 1.11 111.75 0.84 111.39 0.84 isokinetic neck-sc1-jf-f 5/3/05 8:56 AM Page 24 26 SAJSM VOL 17 NO. 1 2005 4. Buck CA Dameron FB, Dow MJ, Skowlund HV. Study of normal range of motion in the neck utilizing a bubble goniometer. Arch Phys Med Rehabil 1959; 40: 390-92. 5. Cantu RC. Head and spine injuries in youth sports. Clin Sports Med 1995; 14: 517 - 32. 6. Du Toit DE. The kinetics of rugby scrumming and the neck s force capa- bilities as a cause of cervical spinal injuries. 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