Clin Physiol Funct Imaging (2015)
doi: 10.1111/cpf.12232
SHORT COMMUNICATION
Gender differences in muscle blood volume reduction in the tibialis anterior muscle during passive plantarflexion Aki Otsuki1, Yoshiho Muraoka2, Emi Fujita3, Sayaka Kubo3, Misaki Yoshida4, Yuko Komuro5, Shigeki Ikegawa6, Yuji Ohta7 and Mayumi Kuno-Mizumura7 1
Research Institute of Physical Fitness, Japan Women’s College of Physical Education, 2Department of Education, Meisei University, 3Faculty of Letters and Education, Ochanomizu University, 4Center for Research and Development of Education, Ochanomizu University, 5Center for Leadership Education and Research, Ochanomizu University, 6Laboratory for Exercise Physiology, Jumonji University, and 7Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo, Japan
Summary Correspondence Aki Otsuki, Research Institute of Physical Fitness, Japan Women’s College of Physical Education, Kita-Karasuyama, Setagaya-ku, Tokyo 1578565, Japan E-mail: [email protected]
Accepted for publication Received 5 August 2014; accepted 6 January 2015
Key words fascicle length; muscle blood volume; muscle extension; muscle oxygenation level; near-infrared spectroscopy; ultrasonography
Physical flexibility, such as joint range of motion and muscle extension, may influence muscle blood volume. Women have been shown to have a greater degree of flexibility than men. We examined whether there is a gender difference in the relationship between fascicle length and muscle blood volume or oxygenation in untrained men and women. In 16 untrained men and thirteen untrained women, we measured the total-[haemoglobin (Hb) + myoglobin (Mb)] (total-[Hb + Mb]) and relative oxy-[Hb + Mb] after calibrating baseline and arterial occlusion deoxygenation levels with near-infrared spectroscopy. Also, fascicle length was measured with B-mode ultrasonography at the tibialis anterior muscle during passive plantarflexion. Increases in fascicle length from baseline (ankle joint angle 120°, composed from the caput fibulae, the malleolus (pivot), and the distal epiphysis of the fifth metatarsal bone) were greater in women than in men during plantarflexion of 140° and 160° and the maximal angle without pain. However, the decreases in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were not different between women and men at any degree of plantarflexion. Moreover, fascicle length and total-[Hb + Mb]/muscle thickness (men > women) showed a similar relationship, with muscle thickness increasing capillary compression. These findings indicate the possibility of a mechanical function underlying muscle blood volume during muscle stretching, which is greater in women than in men.
Introduction Muscle blood volume decreases with muscle stretching; however, this decrease is attenuated in ballet-trained women who have a wider range of motion than control women (Otsuki et al., 2011). Women have been shown to have greater flexibility than men (Grimston et al., 1993), and the attenuated decrease in muscle blood volume during muscle extension may explain a woman’s greater arterial blood flow during exercise (Russ and Kent-Braun 2003; Clark et al., 2005; Parker et al., 2007; Saito et al., 2008). Other factors may also contribute to this smaller decrease including less muscle compression by muscle mass (Sadamoto et al., 1983; Sejersted et al., 1984) and greater vasodilatation (Kneale et al., 2000; Levenson et al., 2001; Parker et al., 2007) mediated by oestrogen (Rogers &
Sheriff, 2004; Adkisson et al., 2010) or other metabolic byproducts (Kent-Braun et al., 2002; Russ et al., 2005) in women compared to men. Women have a wider range of motion and less joint stiffness (Riemann et al., 2001) than men. Furthermore, muscle fascicle length (Chow et al., 2000; Kubo et al., 2003) and extensibility of the muscle–tendon unit (Kato et al., 2005; Morse, 2011) are found to be greater in women than in men. These flexibility factors may increase muscle extension reserve corresponding to the absolute joint angle. Therefore, we hypothesised that muscle is not exposed to compression by muscle stretching in women than in men. We examined muscle blood volume reduction and fascicle length extension in men and women during passive muscle stretching.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
1
2 Fascicle length and NIRS response, A. Otsuki et al.
Methods Experimental design All subjects performed passive plantarflexion at several different ankle joint angles. During plantarflexion, fascicle lengths, and changes in muscle blood volume and muscle oxygenation levels at the tibialis anterior muscle were measured. All data were compared between men and women. Subjects Sixteen men and 13 women voluntarily participated in this study (Table 1). None had exercised regularly either at the recreational or professional level. All subjects were free of signs or symptoms of any overt chronic disease. None of the participants smoked or took any medication. The study was approved by the Ethics Committee of the Institute of Ochanomizu University and conformed to the principles outlined in the Helsinki Declaration. All subjects provided written, informed consent before inclusion in the study. Experimental procedures Subjects performed plantarflexion in the supine position with the knee joint fully extended. The sole of the right foot was fixed to a rotation plate, which matched the rotational axis of the malleolus. The ankle joint angle was defined by the caput fibulae (starting point), the malleolus (fulcrum), and the distal epiphysis of the fifth metatarsal bone (end point). The angle was changed passively from 120° (resting angle; baseline) to 140°, 160°, maximal angle without pain (3° less than the angle at which the subject felt pain) and maximal angle with pain. The ankle joint angles were maintained during plantarflexion by a servo system (X03-0054I; Dyadic Systems, Ishikawa, Japan). Two tests were performed. First, the maximal angle without pain was determined, and the fascicle lengths were measured at baseline, 140°, 160°, maximal angle without pain and the maximal angle with pain. Second, the muscle blood volume and muscle oxygenation level were measured during muscle stretch at 140°, 160° and the maximal angle without pain. Stretches were performed in the following manner: 2-min rest followed by plantarflexion with a 1-min sustained stretch. Table 1
Physiological characteristics of men and women Men
Age, years Height, cm Weight, kg Body mass index, kg/m2 Muscle thickness, cm Subcutaneous fat thickness, cm
24 169 60 21 31 03
Values are means SD. *P < 005 vs. Men.
1 5 10 3 03 01
Data recoding Fascicle length, muscle and subcutaneous fat thicknesses. A linear ultrasonic transducer was placed at the shin perpendicular to the tibialis anterior muscle layer, and a site of maximal muscle thickness was determined in the cross-sectional image by scanning along the long axis of the muscle. Fascicle length was measured in the longitudinal images at this site (Fukunaga et al., 1997; Kawakami et al., 1998) using B-mode ultrasonography (SSD-900; ALOKA, Tokyo, Japan). The fascicle echo from the superficial to the deep aponeurosis was visualised, and the image was printed on recording film. Muscle and subcutaneous fat thicknesses were determined using a marker with ultrasonography. Muscle thickness was measured as the distance between the superficial and deep aponeurosis echoes, and subcutaneous fat thickness was measured as the distance between the skin surface and the superficial aponeurosis echo. Oxygenated (Oxy)-, deoxygenated (Deoxy)-, and total-haemoglobin and myoglobin ([Hb + Mb]) concentration. Using the same muscle site at which fascicle lengths were measured, changes in the concentration of oxy-[Hb + Mb], deoxy-[Hb + Mb] and total-[Hb + Mb] (oxy-[Hb + Mb] + deoxy-[Hb + Mb]) were measured using near-infrared spectroscopy (NIRO-200; Hamamatsu Photonics, Shizuoka, Japan). The device operated at 3 wavelengths: 775, 810 and 850 nm. Optical densities for the 3 wavelengths were acquired with a sampling time of 05 s. The separation between the light source and the detector was 4 cm. Data were recorded to a personal computer with a sampling rate of 1000 Hz through an A/D converter (Power Lab; AD Instruments, Castle Hill, Australia). Data analysis
Women
All measurements were taken in a quiet, temperature-controlled room (25°C). Respiration was controlled throughout each trial by using a 1-s inhalation phase and a 4-s exhalation phase to avoid any influence of the respiratory cycle on the peripheral circulation (Osada et al., 2002; Miller et al., 2005). To obtain 1 data point per 1 respiration cycle (5 s), the timing of the ankle joint change was adjusted at 5-s intervals. The mean speed of changing joint angles was 28 s. In women, measurements were obtained during the early follicular phase, 4–7 days after the initiation of menstruation, to control for any possible influence of the menstrual cycle on circulation.
22 162 51 19 26 06
1* 4* 5* 2* 03* 01*
Fascicle length. The fascicle length was measured using a curvimeter (Comcurve-5; Koizumi, Niigata, Japan). The value was averaged from 3 echo images at each joint angle. Muscle blood volume and muscle oxygenation. Total-[Hb + used as the index of muscle blood volume. The adipose tissue on the optical density of total-[Hb + corrected by dividing measurement sensitivity S
Mb] was effect of Mb] was (S = exp
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Fascicle length and NIRS response, A. Otsuki et al. 3
P < 005 was considered statistically significant. Results are presented as means SD.
{-(h/A1)2}-A2G(a,b); h: subcutaneous fat thickness; A1, A2, a and b: constant determined by source–detector separation; G (a,b): gamma distribution). In addition, total-[Hb + Mb]/ muscle thickness was used to decrease the influence of muscle compression by muscle thickness on total-[Hb + Mb]. The oxy-[Hb + Mb] concentration was measured as the percentage of the difference between baseline and the minimum value recorded during arterial occlusion (Hamaoka et al., 1996; Sako et al., 2001). The calibration trial consisted of a 10-min resting and a 10-min sustained arterial occlusion phase. After the resting phase, the right thigh of the subject was occluded by inflating a pneumatic cuff to 300 mmHg, and complete deoxygenation was confirmed by a plateau in the oxy-[Hb + Mb] concentration. The baseline and minimum values were determined as the average between 8 and 9 min of the resting phase and the minimum value during the last 10 s of the occlusion phase, respectively. The baseline value was defined as 0%, and the minimum value during ischaemia was defined as 100%; the oxy[Hb + Mb] concentration in the stretching trial was calculated relative to these values. Changes in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were averaged at 5-s intervals to match the respiration cycle.
Results Ankle joint angle and fascicle length The ankle joint angle at maximal plantarflexion without pain was greater in women than in men (Table 2). Fascicle lengths extended proportionally as joint angles increased in both men and women. Fascicle lengths from baseline were greater in women than in men at 140°, 160° and at the maximal angle without pain. Muscle blood volume and muscle oxygenation The total-[Hb + Mb] and relative oxy-[Hb + Mb] decreased with muscle stretching. Total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were not different between women and men at 140°, 160°, and at the maximal angle without pain, although muscle extension (fascicle length) was greater in women than in men at all angles (Table 2). Moreover, a similar relationship was observed for total-[Hb + Mb]/muscle thickness (Fig. 1).
Statistical analysis Statistical analysis was performed using two-way repeated measures analysis of variance (ANOVA) followed by Bonferroni’s multiple comparison, if appropriate. The intergroup comparison of characteristics or changes in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline at maximal angle without pain were determined by an unpaired Student’s t-test.
Table 2
Discussion To isolate a possible mechanical factor for the preservation of muscle blood volume, we studied total-[Hb + Mb] changes associated with passive muscle stretching. To minimise any possible hormonal influences in women, studies were performed
Ankle joint angles, fascicle lengths, total-[Hb + Mb], and relative oxy-[Hb + Mb] at baseline and during stretching in men and women Baseline
Fascicle length, mm Changes in fascicle length from baseline, mm Changes in total-[Hb + Mb] from baseline, lmol Changes in relative oxy-[Hb + Mb] from baseline, %
Men Women Men Women Men Women Men Women Baseline
Angle, degree Fascicle length, mm Changes in fascicle length from baseline, mm Changes in total-[Hb + Mb] from baseline, lmol Changes in relative oxy- [Hb + Mb] from baseline, %
Men Women Men Women Men Women Men Women Men Women
87 8 79 14
85 8 79 13
140 degree 91 92 6 13 73 57 1 4
Maximal angle without pain 165 173 99 116 14 37 188 150 14 13
9 8* 8† 25*,† 6 15* 109 91 16 8
160 degree
†
8 17† 4 7* 90 35 5 5
100 109 12 29 165 104 8 7
9‡ 24‡ 6‡ 13*,‡ 80‡ 78‡ 8‡ 5
Maximal angle with pain 175 188 104 127 18 47
8# 11*,# 7# 28*,# 7# 19*,#
Values are means SD. *P < 005 vs. Men. †P < 005 vs. baseline. ‡P < 005 vs. 140 degree. #P < 005 vs. maximal angle without pain. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
4 Fascicle length and NIRS response, A. Otsuki et al.
(μmol)
(a)
Figure 1 The relationship between changes in fascicle length from baseline and changes in total-[Hb + Mb] (a), total-[Hb + Mb]/muscle thickness (b) and relative oxy-[Hb + Mb] (c) from baseline. The reduction in total-[Hb + Mb] was similar in men and women, although fascicle length increase was greater in women than in men. A similar relationship was also observed for total-[Hb + Mb]/muscle thickness or relative oxy-[Hb + Mb] and fascicle length. Men, open notation; women, closed notation; 140°, circle; 160°, triangle; maximal angle without pain, rhomboid.
0
from basline
Changes in total-[Hb + Mb]
100
–100
–200
–300
–400
Men: y = –14·4x + 10·8 Women: y = – 3·7 x – 7·4
0
20
40
60 (mm)
Changes in fascicle length from baseline (b)
(μmol cm-1)
Changes in total-[Hb + Mb] from baseline/muscle thickness
50
0
–50
–100
–150
Men: y = –4·6x + 2·9 Women: y = –1·5x – 2·9
0
20
40
60 (mm)
Changes in fascicle length from baseline (%)
(c)
0
from basline
Changes in relaive oxy-[Hb + Mb]
10
–10
–20
–30
–40
Men: y = –1·5x + 8·0 Women: y = –0·3x + 0·2
0
20
40
Changes in fascicle length from baseline
60 (mm)
on women in the early follicular phase of their menstrual cycles. As oestrogen causes vasodilatation (Rogers & Sheriff, 2004; Adkisson et al., 2010), we chose this low oestrogen phase in the menstrual cycle. At 140°, 160°, and at the maximal angle with-
out pain, the increase in fascicle length from baseline was greater in women than in men (Table 2). However, decreases in total-[Hb + Mb] and relative oxy-[Hb + Mb] were not greater in women than in men (Table 2 and Fig. 1). Muscle blood flow decreases proportionally with fascicle stretching (Nakao & Segal, 1995; Poole et al., 1997) due to a decrease in blood flow through capillaries running parallel to muscle fibres (Nakao & Segal, 1995; Poole et al., 1997) and an increase in intramuscular pressure (Ameredes & Provenzano, 1997). However, muscle blood volume and oxygenation are better preserved in women than in men in the stretched muscle. The attenuation of the decreases in total- and relative oxy[Hb + Mb] during muscle stretching in women in comparison to men may be because intramuscular pressure is elevated to a lesser extent in women. Muscle thickness that contributes to increased intramuscular pressure was greater in men than in women. However, total-[Hb + Mb]/muscle thickness correlated with total-[Hb + Mb] (Fig. 1). Women had wider range of motion and longer fascicle length at maximal plantarflexion than men. Because of the high capacity to increase fascicle length in women, the intramuscular pressure acting on the capillaries may have been lower. Gender differences, such as muscle–tendon unit elasticity (Kato et al., 2005; Morse, 2011), fascicle length (Chow et al., 2000; Kubo et al., 2003) and capillary density, might be associated with a decrease in muscle blood volume during muscle stretching. The relationship between the change in fascicle length and the change in total- or relative oxy-[Hb + Mb] (Fig. 1) in women and men was similar to that seen between ballet-trained flexible women and untrained control women in a previous study (Otsuki et al., 2011). In conclusion, the decrease in total-[Hb + Mb] during muscle stretching was attenuated in women compared to men. Women can extend their muscles dynamically without an excessive reduction in muscle blood volume compared to than observed in men.
Acknowledgments This work was financially supported by a Sasakawa Scientific Research Grant from the Japan Science Society. We would like to thank Professor Tomoko Sadamoto and Associate Professor Kohei Sato for supporting our study.
Conflict of interests The authors have no conflict of interests.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Fascicle length and NIRS response, A. Otsuki et al. 5
References Adkisson EJ, Casey DP, Beck DT, et al. Central, peripheral and resistance arterial reactivity: fluctuates during the phases of the menstrual cycle. Exp Biol Med (Maywood) (2010); 235: 111–118. Ameredes BT, Provenzano MA. Regional intramuscular pressure development and fatigue in the canine gastrocnemius muscle in situ. J Appl Physiol (1985) (1997); 83: 1867–1876. Chow RS, Medri MK, Martin DC, et al. Sonographic studies of human soleus and gastrocnemius muscle architecture: gender variability. Eur J Appl Physiol (2000); 82: 236–244. Clark BC, Collier SR, Manini TM, et al. Sex differences in muscle fatigability and activation patterns of the human quadriceps femoris. Eur J Appl Physiol (2005); 94: 196–206. Fukunaga T, Ichinose Y, Ito M, et al. Determination of fascicle length and pennation in a contracting human muscle in vivo. J Appl Physiol (1985) (1997); 82: 354–358. Grimston SK, Nigg BM, Hanley DA, et al. Differences in ankle joint complex range of motion as a function of age. Foot Ankle (1993); 14: 215–222. Hamaoka T, Iwane H, Shimomitsu T, et al. Noninvasive measures of oxidative metabolism on working human muscles by nearinfrared spectroscopy. J Appl Physiol (1985) (1996); 81: 1410–1417. Kato E, Oda T, Chino K, et al. Musculotendinous factors influencing difference in ankle joint flexibility between women and men. Int J Sport Health Sci (2005); 3: 218–225. Kawakami Y, Ichinose Y, Fukunaga T. Architectural and functional features of human triceps surae muscles during contraction. J Appl Physiol (1985) (1998); 85: 398–404. Kent-Braun JA, Ng AV, Doyle JW, et al. Human skeletal muscle responses vary with age and gender during fatigue due to
incremental isometric exercise. J Appl Physiol (1985) (2002); 93: 1813–1823. Kneale BJ, Chowienczyk PJ, Brett SE, et al. Gender differences in sensitivity to adrenergic agonists of forearm resistance vasculature. J Am Coll Cardiol (2000); 36: 1233–1238. Kubo K, Kanehisa H, Azuma K, et al. Muscle architectural characteristics in young and elderly men and women. Int J Sports Med (2003); 24: 125–130. Levenson J, Pessana F, Gariepy J, et al. Gender differences in wall shear-mediated brachial artery vasoconstriction and vasodilation. J Am Coll Cardiol (2001); 38: 1668–1674. Miller JD, Pegelow DF, Jacques AJ, et al. Effects of augmented respiratory muscle pressure production on locomotor limb venous return during calf contraction exercise. J Appl Physiol (1985) (2005); 99: 1802– 1815. Morse CI. Gender differences in the passive stiffness of the human gastrocnemius muscle during stretch. Eur J Appl Physiol (2011); 111: 2149–2154. Nakao M, Segal SS. Muscle length alters geometry of arterioles and venules in hamster retractor. Am J Physiol (1995); 268: H336–H344. Osada T, Katsumura T, Hamaoka T, et al. Quantitative effects of respiration on venous return during single knee extension-flexion. Int J Sports Med (2002); 23: 183–190. Otsuki A, Fujita E, Ikegawa S, et al. Muscle oxygenation and fascicle length during passive muscle stretching in ballet-trained subjects. Int J Sports Med (2011); 32: 496–502. Parker BA, Smithmyer SL, Pelberg JA, et al. Sex differences in leg vasodilation during graded knee extensor exercise in young adults. J Appl Physiol (1985) (2007); 103: 1583–1591.
Poole DC, Musch TI, Kindig CA. In vivo microvascular structural and functional consequences of muscle length changes. Am J Physiol (1997); 272: H2107–H2114. Riemann BL, DeMont RG, Ryu K, et al. The effects of sex, joint angle, and the gastrocnemius muscle on passive ankle joint complex stiffness. J Athl Train (2001); 36: 369–375. Rogers J, Sheriff DD. Role of estrogen in nitric oxide- and prostaglandin-dependent modulation of vascular conductance during treadmill locomotion in rats. J Appl Physiol (1985) (2004); 97: 756–763. Russ DW, Kent-Braun JA. Sex differences in human skeletal muscle fatigue are eliminated under ischemic conditions. J Appl Physiol (1985) (2003); 94: 2414– 2422. Russ DW, Lanza IR, Rothman D, et al. Sex differences in glycolysis during brief, intense isometric contractions. Muscle Nerve (2005); 32: 647–655. Sadamoto T, Bonde-Petersen F, Suzuki Y. Skeletal muscle tension, flow, pressure, and EMG during sustained isometric contractions in humans. Eur J Appl Physiol Occup Physiol (1983); 51: 395–408. Saito Y, Iemitsu M, Otsuki T, et al. Gender differences in brachial blood flow during fatiguing intermittent handgrip. Med Sci Sports Exerc (2008); 40: 684–690. Sako T, Hamaoka T, Higuchi H, et al. Validity of NIR spectroscopy for quantitatively measuring muscle oxidative metabolic rate in exercise. J Appl Physiol (1985) (2001); 90: 338–344. Sejersted OM, Hargens AR, Kardel KR, et al. Intramuscular fluid pressure during isometric contraction of human skeletal muscle. J Appl Physiol Respir Environ Exerc Physiol (1984); 56: 287–295.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
doi: 10.1111/cpf.12232
SHORT COMMUNICATION
Gender differences in muscle blood volume reduction in the tibialis anterior muscle during passive plantarflexion Aki Otsuki1, Yoshiho Muraoka2, Emi Fujita3, Sayaka Kubo3, Misaki Yoshida4, Yuko Komuro5, Shigeki Ikegawa6, Yuji Ohta7 and Mayumi Kuno-Mizumura7 1
Research Institute of Physical Fitness, Japan Women’s College of Physical Education, 2Department of Education, Meisei University, 3Faculty of Letters and Education, Ochanomizu University, 4Center for Research and Development of Education, Ochanomizu University, 5Center for Leadership Education and Research, Ochanomizu University, 6Laboratory for Exercise Physiology, Jumonji University, and 7Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo, Japan
Summary Correspondence Aki Otsuki, Research Institute of Physical Fitness, Japan Women’s College of Physical Education, Kita-Karasuyama, Setagaya-ku, Tokyo 1578565, Japan E-mail: [email protected]
Accepted for publication Received 5 August 2014; accepted 6 January 2015
Key words fascicle length; muscle blood volume; muscle extension; muscle oxygenation level; near-infrared spectroscopy; ultrasonography
Physical flexibility, such as joint range of motion and muscle extension, may influence muscle blood volume. Women have been shown to have a greater degree of flexibility than men. We examined whether there is a gender difference in the relationship between fascicle length and muscle blood volume or oxygenation in untrained men and women. In 16 untrained men and thirteen untrained women, we measured the total-[haemoglobin (Hb) + myoglobin (Mb)] (total-[Hb + Mb]) and relative oxy-[Hb + Mb] after calibrating baseline and arterial occlusion deoxygenation levels with near-infrared spectroscopy. Also, fascicle length was measured with B-mode ultrasonography at the tibialis anterior muscle during passive plantarflexion. Increases in fascicle length from baseline (ankle joint angle 120°, composed from the caput fibulae, the malleolus (pivot), and the distal epiphysis of the fifth metatarsal bone) were greater in women than in men during plantarflexion of 140° and 160° and the maximal angle without pain. However, the decreases in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were not different between women and men at any degree of plantarflexion. Moreover, fascicle length and total-[Hb + Mb]/muscle thickness (men > women) showed a similar relationship, with muscle thickness increasing capillary compression. These findings indicate the possibility of a mechanical function underlying muscle blood volume during muscle stretching, which is greater in women than in men.
Introduction Muscle blood volume decreases with muscle stretching; however, this decrease is attenuated in ballet-trained women who have a wider range of motion than control women (Otsuki et al., 2011). Women have been shown to have greater flexibility than men (Grimston et al., 1993), and the attenuated decrease in muscle blood volume during muscle extension may explain a woman’s greater arterial blood flow during exercise (Russ and Kent-Braun 2003; Clark et al., 2005; Parker et al., 2007; Saito et al., 2008). Other factors may also contribute to this smaller decrease including less muscle compression by muscle mass (Sadamoto et al., 1983; Sejersted et al., 1984) and greater vasodilatation (Kneale et al., 2000; Levenson et al., 2001; Parker et al., 2007) mediated by oestrogen (Rogers &
Sheriff, 2004; Adkisson et al., 2010) or other metabolic byproducts (Kent-Braun et al., 2002; Russ et al., 2005) in women compared to men. Women have a wider range of motion and less joint stiffness (Riemann et al., 2001) than men. Furthermore, muscle fascicle length (Chow et al., 2000; Kubo et al., 2003) and extensibility of the muscle–tendon unit (Kato et al., 2005; Morse, 2011) are found to be greater in women than in men. These flexibility factors may increase muscle extension reserve corresponding to the absolute joint angle. Therefore, we hypothesised that muscle is not exposed to compression by muscle stretching in women than in men. We examined muscle blood volume reduction and fascicle length extension in men and women during passive muscle stretching.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
1
2 Fascicle length and NIRS response, A. Otsuki et al.
Methods Experimental design All subjects performed passive plantarflexion at several different ankle joint angles. During plantarflexion, fascicle lengths, and changes in muscle blood volume and muscle oxygenation levels at the tibialis anterior muscle were measured. All data were compared between men and women. Subjects Sixteen men and 13 women voluntarily participated in this study (Table 1). None had exercised regularly either at the recreational or professional level. All subjects were free of signs or symptoms of any overt chronic disease. None of the participants smoked or took any medication. The study was approved by the Ethics Committee of the Institute of Ochanomizu University and conformed to the principles outlined in the Helsinki Declaration. All subjects provided written, informed consent before inclusion in the study. Experimental procedures Subjects performed plantarflexion in the supine position with the knee joint fully extended. The sole of the right foot was fixed to a rotation plate, which matched the rotational axis of the malleolus. The ankle joint angle was defined by the caput fibulae (starting point), the malleolus (fulcrum), and the distal epiphysis of the fifth metatarsal bone (end point). The angle was changed passively from 120° (resting angle; baseline) to 140°, 160°, maximal angle without pain (3° less than the angle at which the subject felt pain) and maximal angle with pain. The ankle joint angles were maintained during plantarflexion by a servo system (X03-0054I; Dyadic Systems, Ishikawa, Japan). Two tests were performed. First, the maximal angle without pain was determined, and the fascicle lengths were measured at baseline, 140°, 160°, maximal angle without pain and the maximal angle with pain. Second, the muscle blood volume and muscle oxygenation level were measured during muscle stretch at 140°, 160° and the maximal angle without pain. Stretches were performed in the following manner: 2-min rest followed by plantarflexion with a 1-min sustained stretch. Table 1
Physiological characteristics of men and women Men
Age, years Height, cm Weight, kg Body mass index, kg/m2 Muscle thickness, cm Subcutaneous fat thickness, cm
24 169 60 21 31 03
Values are means SD. *P < 005 vs. Men.
1 5 10 3 03 01
Data recoding Fascicle length, muscle and subcutaneous fat thicknesses. A linear ultrasonic transducer was placed at the shin perpendicular to the tibialis anterior muscle layer, and a site of maximal muscle thickness was determined in the cross-sectional image by scanning along the long axis of the muscle. Fascicle length was measured in the longitudinal images at this site (Fukunaga et al., 1997; Kawakami et al., 1998) using B-mode ultrasonography (SSD-900; ALOKA, Tokyo, Japan). The fascicle echo from the superficial to the deep aponeurosis was visualised, and the image was printed on recording film. Muscle and subcutaneous fat thicknesses were determined using a marker with ultrasonography. Muscle thickness was measured as the distance between the superficial and deep aponeurosis echoes, and subcutaneous fat thickness was measured as the distance between the skin surface and the superficial aponeurosis echo. Oxygenated (Oxy)-, deoxygenated (Deoxy)-, and total-haemoglobin and myoglobin ([Hb + Mb]) concentration. Using the same muscle site at which fascicle lengths were measured, changes in the concentration of oxy-[Hb + Mb], deoxy-[Hb + Mb] and total-[Hb + Mb] (oxy-[Hb + Mb] + deoxy-[Hb + Mb]) were measured using near-infrared spectroscopy (NIRO-200; Hamamatsu Photonics, Shizuoka, Japan). The device operated at 3 wavelengths: 775, 810 and 850 nm. Optical densities for the 3 wavelengths were acquired with a sampling time of 05 s. The separation between the light source and the detector was 4 cm. Data were recorded to a personal computer with a sampling rate of 1000 Hz through an A/D converter (Power Lab; AD Instruments, Castle Hill, Australia). Data analysis
Women
All measurements were taken in a quiet, temperature-controlled room (25°C). Respiration was controlled throughout each trial by using a 1-s inhalation phase and a 4-s exhalation phase to avoid any influence of the respiratory cycle on the peripheral circulation (Osada et al., 2002; Miller et al., 2005). To obtain 1 data point per 1 respiration cycle (5 s), the timing of the ankle joint change was adjusted at 5-s intervals. The mean speed of changing joint angles was 28 s. In women, measurements were obtained during the early follicular phase, 4–7 days after the initiation of menstruation, to control for any possible influence of the menstrual cycle on circulation.
22 162 51 19 26 06
1* 4* 5* 2* 03* 01*
Fascicle length. The fascicle length was measured using a curvimeter (Comcurve-5; Koizumi, Niigata, Japan). The value was averaged from 3 echo images at each joint angle. Muscle blood volume and muscle oxygenation. Total-[Hb + used as the index of muscle blood volume. The adipose tissue on the optical density of total-[Hb + corrected by dividing measurement sensitivity S
Mb] was effect of Mb] was (S = exp
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Fascicle length and NIRS response, A. Otsuki et al. 3
P < 005 was considered statistically significant. Results are presented as means SD.
{-(h/A1)2}-A2G(a,b); h: subcutaneous fat thickness; A1, A2, a and b: constant determined by source–detector separation; G (a,b): gamma distribution). In addition, total-[Hb + Mb]/ muscle thickness was used to decrease the influence of muscle compression by muscle thickness on total-[Hb + Mb]. The oxy-[Hb + Mb] concentration was measured as the percentage of the difference between baseline and the minimum value recorded during arterial occlusion (Hamaoka et al., 1996; Sako et al., 2001). The calibration trial consisted of a 10-min resting and a 10-min sustained arterial occlusion phase. After the resting phase, the right thigh of the subject was occluded by inflating a pneumatic cuff to 300 mmHg, and complete deoxygenation was confirmed by a plateau in the oxy-[Hb + Mb] concentration. The baseline and minimum values were determined as the average between 8 and 9 min of the resting phase and the minimum value during the last 10 s of the occlusion phase, respectively. The baseline value was defined as 0%, and the minimum value during ischaemia was defined as 100%; the oxy[Hb + Mb] concentration in the stretching trial was calculated relative to these values. Changes in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were averaged at 5-s intervals to match the respiration cycle.
Results Ankle joint angle and fascicle length The ankle joint angle at maximal plantarflexion without pain was greater in women than in men (Table 2). Fascicle lengths extended proportionally as joint angles increased in both men and women. Fascicle lengths from baseline were greater in women than in men at 140°, 160° and at the maximal angle without pain. Muscle blood volume and muscle oxygenation The total-[Hb + Mb] and relative oxy-[Hb + Mb] decreased with muscle stretching. Total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline were not different between women and men at 140°, 160°, and at the maximal angle without pain, although muscle extension (fascicle length) was greater in women than in men at all angles (Table 2). Moreover, a similar relationship was observed for total-[Hb + Mb]/muscle thickness (Fig. 1).
Statistical analysis Statistical analysis was performed using two-way repeated measures analysis of variance (ANOVA) followed by Bonferroni’s multiple comparison, if appropriate. The intergroup comparison of characteristics or changes in total-[Hb + Mb] and relative oxy-[Hb + Mb] from baseline at maximal angle without pain were determined by an unpaired Student’s t-test.
Table 2
Discussion To isolate a possible mechanical factor for the preservation of muscle blood volume, we studied total-[Hb + Mb] changes associated with passive muscle stretching. To minimise any possible hormonal influences in women, studies were performed
Ankle joint angles, fascicle lengths, total-[Hb + Mb], and relative oxy-[Hb + Mb] at baseline and during stretching in men and women Baseline
Fascicle length, mm Changes in fascicle length from baseline, mm Changes in total-[Hb + Mb] from baseline, lmol Changes in relative oxy-[Hb + Mb] from baseline, %
Men Women Men Women Men Women Men Women Baseline
Angle, degree Fascicle length, mm Changes in fascicle length from baseline, mm Changes in total-[Hb + Mb] from baseline, lmol Changes in relative oxy- [Hb + Mb] from baseline, %
Men Women Men Women Men Women Men Women Men Women
87 8 79 14
85 8 79 13
140 degree 91 92 6 13 73 57 1 4
Maximal angle without pain 165 173 99 116 14 37 188 150 14 13
9 8* 8† 25*,† 6 15* 109 91 16 8
160 degree
†
8 17† 4 7* 90 35 5 5
100 109 12 29 165 104 8 7
9‡ 24‡ 6‡ 13*,‡ 80‡ 78‡ 8‡ 5
Maximal angle with pain 175 188 104 127 18 47
8# 11*,# 7# 28*,# 7# 19*,#
Values are means SD. *P < 005 vs. Men. †P < 005 vs. baseline. ‡P < 005 vs. 140 degree. #P < 005 vs. maximal angle without pain. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
4 Fascicle length and NIRS response, A. Otsuki et al.
(μmol)
(a)
Figure 1 The relationship between changes in fascicle length from baseline and changes in total-[Hb + Mb] (a), total-[Hb + Mb]/muscle thickness (b) and relative oxy-[Hb + Mb] (c) from baseline. The reduction in total-[Hb + Mb] was similar in men and women, although fascicle length increase was greater in women than in men. A similar relationship was also observed for total-[Hb + Mb]/muscle thickness or relative oxy-[Hb + Mb] and fascicle length. Men, open notation; women, closed notation; 140°, circle; 160°, triangle; maximal angle without pain, rhomboid.
0
from basline
Changes in total-[Hb + Mb]
100
–100
–200
–300
–400
Men: y = –14·4x + 10·8 Women: y = – 3·7 x – 7·4
0
20
40
60 (mm)
Changes in fascicle length from baseline (b)
(μmol cm-1)
Changes in total-[Hb + Mb] from baseline/muscle thickness
50
0
–50
–100
–150
Men: y = –4·6x + 2·9 Women: y = –1·5x – 2·9
0
20
40
60 (mm)
Changes in fascicle length from baseline (%)
(c)
0
from basline
Changes in relaive oxy-[Hb + Mb]
10
–10
–20
–30
–40
Men: y = –1·5x + 8·0 Women: y = –0·3x + 0·2
0
20
40
Changes in fascicle length from baseline
60 (mm)
on women in the early follicular phase of their menstrual cycles. As oestrogen causes vasodilatation (Rogers & Sheriff, 2004; Adkisson et al., 2010), we chose this low oestrogen phase in the menstrual cycle. At 140°, 160°, and at the maximal angle with-
out pain, the increase in fascicle length from baseline was greater in women than in men (Table 2). However, decreases in total-[Hb + Mb] and relative oxy-[Hb + Mb] were not greater in women than in men (Table 2 and Fig. 1). Muscle blood flow decreases proportionally with fascicle stretching (Nakao & Segal, 1995; Poole et al., 1997) due to a decrease in blood flow through capillaries running parallel to muscle fibres (Nakao & Segal, 1995; Poole et al., 1997) and an increase in intramuscular pressure (Ameredes & Provenzano, 1997). However, muscle blood volume and oxygenation are better preserved in women than in men in the stretched muscle. The attenuation of the decreases in total- and relative oxy[Hb + Mb] during muscle stretching in women in comparison to men may be because intramuscular pressure is elevated to a lesser extent in women. Muscle thickness that contributes to increased intramuscular pressure was greater in men than in women. However, total-[Hb + Mb]/muscle thickness correlated with total-[Hb + Mb] (Fig. 1). Women had wider range of motion and longer fascicle length at maximal plantarflexion than men. Because of the high capacity to increase fascicle length in women, the intramuscular pressure acting on the capillaries may have been lower. Gender differences, such as muscle–tendon unit elasticity (Kato et al., 2005; Morse, 2011), fascicle length (Chow et al., 2000; Kubo et al., 2003) and capillary density, might be associated with a decrease in muscle blood volume during muscle stretching. The relationship between the change in fascicle length and the change in total- or relative oxy-[Hb + Mb] (Fig. 1) in women and men was similar to that seen between ballet-trained flexible women and untrained control women in a previous study (Otsuki et al., 2011). In conclusion, the decrease in total-[Hb + Mb] during muscle stretching was attenuated in women compared to men. Women can extend their muscles dynamically without an excessive reduction in muscle blood volume compared to than observed in men.
Acknowledgments This work was financially supported by a Sasakawa Scientific Research Grant from the Japan Science Society. We would like to thank Professor Tomoko Sadamoto and Associate Professor Kohei Sato for supporting our study.
Conflict of interests The authors have no conflict of interests.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd
Fascicle length and NIRS response, A. Otsuki et al. 5
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