- Email: [email protected]
A COMPARISON OF ABDOMINAL MUSCLE ACTIVATION, STRENGTH AND ENDURANCE IN WOMEN WITH FULL-TERM BIRTH EXPERIENCE AND NULLIPAROUS WOMEN
Poster 253, Poster Session 2/Rehabilitation. 14:10-15:10, Room 103 & Alley Area
S728
A COMPARISON OF ABDOMINAL MUSCLE ACTIVATION, STRENGTH AND ENDURANCE IN WOMEN WITH FULL-TERM BIRTH EXPERIENCE AND NULLIPAROUS WOMEN L-J Liaw1,2,5, M-F Liu2,3,5, A-T Hsu1,6, S-M Liu4, S-F Hsiao2,4,5 Institute of Allied Health Sciences, National Cheng Kung University, Tainan, Taiwan, 2 Faculty of Physical Therapy, Kaohsiung Medical University, Kaohsiung,Taiwan 3 Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan, 4 Division of Movement Behavior Sciences, Institute of Behavior Sciences, Kaohsiung Medical University, Taiwan 5 Department of Rehabilitation Medicine, Kaohsiung Medical University Hospital, Kaohsiung,Taiwan 6 Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan; email: [email protected] 1
INTRODUCTION Increases in the anterior and lateral abdominal dimensions were reported in pregnant and postpartum women. Such changes not only affect the body image and the posture of women involved but also compromise the normal body mechanics and the kinesiology of the abdominal corset muscles [1,2]. However, the recovery of abdominal muscle performance in women with birth experience has been questioned despite the prescriptions of abdominal exercises during postnatal physical therapy [3]. This study investigated the activation, strength and endurance of abdominal muscles in the women with and without birth experience.
The role of the abdominal muscles in enhancing trunk stabilization and increasing intra-abdominal pressure is well recognized [4]. The occurrence of low back pain may be increased if the performance of the abdominal muscles is compromised. The result of this study also demonstrates a likely relationship between back pain intensity and endurance of trunk rotation. Therefore, assessing the functional capabilities of abdominal muscle is warranted in postpartum women. This study underscores the need and importance of a better XQGHUVWDQGLQJ RI ZRPHQ¶s trunk muscle performances after child birth and hopefully may lead to better utilization of physical therapy in treating related dysfunctions associated with pregnancy. ˄ˇ˃
RESULTS AND DISCUSSION Between the PP and NP groups, there was no significant difference in SEMG activity of all muscle groups investigated during curl-ups. The external oblique had the highest SEMG output among muscles tested (Figure 1). Despite the similar performance in SEMG, the abdominal strength and endurance were found to be lower in trunk movements such as curl-up and rotation in the PP group (Table 1). The strength of correlations between back pain intensity and endurance of trunk rotation in the PP group was moderate (r = 0.43 and 0.39 for static and dynamic endurance respectively; p<0.05). Abdominal strength was not correlated with the back pain intensity.
Journal of Biomechanics 40(S2)
˄ˆ˃
ˡ̂̅̀˴˿˼̍˸˷ ˘ˠ˚ ʻʸˠ˩˖ʼ
METHODS After signing the informed consents, 30 women with full-term birth experience (the PP group; mean age 34.6±4.0 years; time since last child birth 2.5±1.2 years) and 23 nulliparaous females (the NP group; mean age 33.4±5.7 years) were recruited for this study. Surface electromyography (SEMG) was used to assess muscle activity from the upper and lower rectus abdominis, external and internal oblique during a series of curl-ups. SEMG was normalized to the maximum voluntary muscle contractions respectively. The strength of abdominal muscles was measured by the average of 3 maximal voluntary contractions (MVCs) taken with a hand-held dynamometer. Static and dynamic endurance performance of the abdominal muscles was also recorded. A visual analogue scale was used to document the severity of low back pain in the PP group. Differences in muscle activity were assessed by a one-way repeated-measures analysis of variance. Strength and endurance were compared between two groups using independent t-tests. The relationship between back pain and abdominal strength or endurance was investigated with Pearson¶s correlation coefficient.
˄˅˃
˄˄˃
˄˃˃
ˌ˃
˚˥ˢ˨ˣ ˋ˃
˖̂́̇̅̂˿ ˘̋̃˸̅˼̀˸́̇˴˿
ˊ˃ ˨˥˔
˟˥˔
˘ˢ
˜ˢ
Figure 1: Normalized SEMG activity (mean) during curl-up in the PP (experimental) and NP (control) groups. URA: upper rectus abdominis; LRA lower rectus abdominis; EO: external oblique; IO: internal oblique. Table 1: Abdominal muscle strength and durance in PP (n=30) and NP (n=23) groups. Women with birth experience Mean ̈́ SE
nulliparous women Mean ̈́ SE
p
Strength (Newton) Trunk flexor 234.8 ̈́ 10.9 261.7 ̈́ 7.2 0.046* Trunk rotator 182.9 ̈́ 6.0 199.2 ̈́ 4.7 0.046* Trunk extensor 308.9 ̈́ 7.7 299.4 ̈́ 7.1 0.383 Ratio (flexor/extensor) 0.77 ̈́ 0.04 0.89 ̈́ 0.03 0.022* Static endurance (seconds/time) Trunk flexor 18.8 ̈́ 3.0 60.2 ̈́ 9.8 <0.001* Trunk rotator 30.3 ̈́ 4.9 75.0 ̈́ 14.2 0.006* Dynamic endurance (repetitions) Trunk flexor 15.6 ̈́ 2.3 29.5 ̈́ 1.9 <0.001* Trunk rotator 18.6 ̈́ 2.1 35.0 ̈́ 4.7 0.003* *Significant differences between involved and noninvolved sides (p < .05).
REFERENCES 1. Gilleard WL, et al.. Phys Ther 76, 750-762, 1996. 2. Polden M, et al.. Physiotherapy in Obsterics and Gynaecology. Oxford: Butterworth-Heinemann, 223-52, 1990. 3. Boissonnault et al.. Obsteric and Gynecologic Physical Therapy, NY: Churchill Livingstone, 63-82, 1988. 4. Hodges PW, et al.. Phys Ther, 77, 132-42, 1997. XXI ISB Congress, Poster Sessions, Thursday 5 July 2007
S728
A COMPARISON OF ABDOMINAL MUSCLE ACTIVATION, STRENGTH AND ENDURANCE IN WOMEN WITH FULL-TERM BIRTH EXPERIENCE AND NULLIPAROUS WOMEN L-J Liaw1,2,5, M-F Liu2,3,5, A-T Hsu1,6, S-M Liu4, S-F Hsiao2,4,5 Institute of Allied Health Sciences, National Cheng Kung University, Tainan, Taiwan, 2 Faculty of Physical Therapy, Kaohsiung Medical University, Kaohsiung,Taiwan 3 Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan, 4 Division of Movement Behavior Sciences, Institute of Behavior Sciences, Kaohsiung Medical University, Taiwan 5 Department of Rehabilitation Medicine, Kaohsiung Medical University Hospital, Kaohsiung,Taiwan 6 Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan; email: [email protected] 1
INTRODUCTION Increases in the anterior and lateral abdominal dimensions were reported in pregnant and postpartum women. Such changes not only affect the body image and the posture of women involved but also compromise the normal body mechanics and the kinesiology of the abdominal corset muscles [1,2]. However, the recovery of abdominal muscle performance in women with birth experience has been questioned despite the prescriptions of abdominal exercises during postnatal physical therapy [3]. This study investigated the activation, strength and endurance of abdominal muscles in the women with and without birth experience.
The role of the abdominal muscles in enhancing trunk stabilization and increasing intra-abdominal pressure is well recognized [4]. The occurrence of low back pain may be increased if the performance of the abdominal muscles is compromised. The result of this study also demonstrates a likely relationship between back pain intensity and endurance of trunk rotation. Therefore, assessing the functional capabilities of abdominal muscle is warranted in postpartum women. This study underscores the need and importance of a better XQGHUVWDQGLQJ RI ZRPHQ¶s trunk muscle performances after child birth and hopefully may lead to better utilization of physical therapy in treating related dysfunctions associated with pregnancy. ˄ˇ˃
RESULTS AND DISCUSSION Between the PP and NP groups, there was no significant difference in SEMG activity of all muscle groups investigated during curl-ups. The external oblique had the highest SEMG output among muscles tested (Figure 1). Despite the similar performance in SEMG, the abdominal strength and endurance were found to be lower in trunk movements such as curl-up and rotation in the PP group (Table 1). The strength of correlations between back pain intensity and endurance of trunk rotation in the PP group was moderate (r = 0.43 and 0.39 for static and dynamic endurance respectively; p<0.05). Abdominal strength was not correlated with the back pain intensity.
Journal of Biomechanics 40(S2)
˄ˆ˃
ˡ̂̅̀˴˿˼̍˸˷ ˘ˠ˚ ʻʸˠ˩˖ʼ
METHODS After signing the informed consents, 30 women with full-term birth experience (the PP group; mean age 34.6±4.0 years; time since last child birth 2.5±1.2 years) and 23 nulliparaous females (the NP group; mean age 33.4±5.7 years) were recruited for this study. Surface electromyography (SEMG) was used to assess muscle activity from the upper and lower rectus abdominis, external and internal oblique during a series of curl-ups. SEMG was normalized to the maximum voluntary muscle contractions respectively. The strength of abdominal muscles was measured by the average of 3 maximal voluntary contractions (MVCs) taken with a hand-held dynamometer. Static and dynamic endurance performance of the abdominal muscles was also recorded. A visual analogue scale was used to document the severity of low back pain in the PP group. Differences in muscle activity were assessed by a one-way repeated-measures analysis of variance. Strength and endurance were compared between two groups using independent t-tests. The relationship between back pain and abdominal strength or endurance was investigated with Pearson¶s correlation coefficient.
˄˅˃
˄˄˃
˄˃˃
ˌ˃
˚˥ˢ˨ˣ ˋ˃
˖̂́̇̅̂˿ ˘̋̃˸̅˼̀˸́̇˴˿
ˊ˃ ˨˥˔
˟˥˔
˘ˢ
˜ˢ
Figure 1: Normalized SEMG activity (mean) during curl-up in the PP (experimental) and NP (control) groups. URA: upper rectus abdominis; LRA lower rectus abdominis; EO: external oblique; IO: internal oblique. Table 1: Abdominal muscle strength and durance in PP (n=30) and NP (n=23) groups. Women with birth experience Mean ̈́ SE
nulliparous women Mean ̈́ SE
p
Strength (Newton) Trunk flexor 234.8 ̈́ 10.9 261.7 ̈́ 7.2 0.046* Trunk rotator 182.9 ̈́ 6.0 199.2 ̈́ 4.7 0.046* Trunk extensor 308.9 ̈́ 7.7 299.4 ̈́ 7.1 0.383 Ratio (flexor/extensor) 0.77 ̈́ 0.04 0.89 ̈́ 0.03 0.022* Static endurance (seconds/time) Trunk flexor 18.8 ̈́ 3.0 60.2 ̈́ 9.8 <0.001* Trunk rotator 30.3 ̈́ 4.9 75.0 ̈́ 14.2 0.006* Dynamic endurance (repetitions) Trunk flexor 15.6 ̈́ 2.3 29.5 ̈́ 1.9 <0.001* Trunk rotator 18.6 ̈́ 2.1 35.0 ̈́ 4.7 0.003* *Significant differences between involved and noninvolved sides (p < .05).
REFERENCES 1. Gilleard WL, et al.. Phys Ther 76, 750-762, 1996. 2. Polden M, et al.. Physiotherapy in Obsterics and Gynaecology. Oxford: Butterworth-Heinemann, 223-52, 1990. 3. Boissonnault et al.. Obsteric and Gynecologic Physical Therapy, NY: Churchill Livingstone, 63-82, 1988. 4. Hodges PW, et al.. Phys Ther, 77, 132-42, 1997. XXI ISB Congress, Poster Sessions, Thursday 5 July 2007