The study aims to determine the effects of smartphone use on the muscle activity of the lower extremity when walking. Twenty-three healthy young students were asked to perform a 10-m walk test between normal walking without using a smartphone and walking while two-handed texting on a smartphone. The electromyography activities of the lower extremity were quantified. To quantitatively assess the cervical flexion range of smartphone users, the cervical flexion angle was measured using a digital goniometer. The study results indicated that the use of a smartphone while walking could lessen muscle activity on the tibialis anterior, gastrocnemius, rectus femoris, gluteus maximus, and gluteus medius than that of normal walking without using a smartphone. The walking speeds were reduced in walking while using a smartphone compared with normal walking without using a smartphone. The cervical flexion angle was greater when walking while using a smartphone compared to that of normal walking without using a smartphone. These results suggest that frequently using a smartphone while walking could be a potential risk for musculoskeletal problems.
Walking has been associated with many advantages for people’s well-being and physical health (
Electromyography (EMG) has been used to monitor the electrical activity in the lower limb muscles (
Smartphones are considered a necessary part of the daily life in all age groups. An estimated 77% of the world’s population owns a smartphone, where texting emerged as a quick and cost-effective communication method (
A previous research has shown that using a smartphone while walking leads to changes in gait, characterized by decreased step length, increased step width, longer standing on each limb, and a decrease in swing time (
Recently, healthy young individuals walked with more thoracic kyphosis and lumbar lordosis when using a smartphone compared to when walking without using a smartphone. The results show that the routine use of a smartphone while walking could be a risk for low back pain and musculoskeletal disorders (
However, no study has yet quantified the EMG of the lower extremity muscles when using a smartphone while walking. To further explore the effects of smartphone use on walking, we examined and compared the EMG amplitudes of the lower extremity muscles during normal walking without using a smartphone and texting on a smartphone while walking. We hypothesized that walking while using a smartphone would change the lower extremity muscle activity compared to normal walking.
Twenty-three healthy young students (14 males, 9 females) were recruited from the university community, with the inclusion criteria of belonging to the study target. The exclusion criteria were having a history of fracture of the pelvis and the lower extremity, diseases affecting walking, and not understanding the evaluator’s commands. In our survey, it was reported that the participants spend an average of 329.13±61.92 min per day using smartphones. The subject characteristics are presented in
Each participant walked flat on the ground in two different conditions: normal walking without using a smartphone and walking while conducting two-handed texting on a smartphone. The subjects were asked to text the first verse of the national anthem. After shaving, debriding, and cleaning the skin surface, electrodes were placed over the following eight right lower limb muscles: gluteus maximus and medius, biceps femoris, rectus femoris, gastrocnemius (medial and lateral parts), tibialis anterior, and soleus. With a tape, the surface electrodes were positioned longitudinally over the abdominal muscle, approximately in the direction of the muscle fibers, according to the SENIAM recommendations (
To acquire EMG signals, the surface EMG data were recorded using a Trigno wireless EMG system (Delsys, Inc., Boston, MA, USA). Data analysis was performed using the EMGworks software package (ver. 4.0; Delsys). The sampling rate for the EMG signal was set at 2,000 Hz and the band-pass filter between 20 and 450 Hz. The raw data from the muscles were transformed into the root mean square data. A reference voluntary contraction (RVC) was used to normalize EMG data (
The 10-m walk test (10-MWT) is a simple assessment to measure walking ability in clinical settings, where an individual independently walked a 14-m distance. The time taken for the intermediate 10 m is measured, allowing acceleration and deceleration. It can be either tested at the preferred walking speed.
The cervical flexion angle in the sagittal plane was measured from each participant while walking and texting on a smartphone and while normal walking without using a smartphone after 10-MWT immediately. The digital goniometer axis was placed at the external auditory meatus and the stationary arm perpendicular to floor. Finally, the moving arm was placed at the base of the nostrils. In the 0 starting position for measuring the cervical flexion range of motion, the goniometer reads 90°, which should be transposed and recorded as 0°.
Statistical analyses were performed using the IBM SPSS ver. 18.0 (IBM Co., Armonk, NY, USA), where the data were expressed as means±standard deviations. The differences between normal walking without using a smartphone and walking while texting on a smartphone were assessed by performing the Wilcoxon signed-rank test, considering a
For walking without using a smartphone and walking while using a smartphone, the mean normalized EMG values of the tibialis anterior were 689.07%±441.75% and 595.08%±400.86%, medial gastrocnemius 1,040.37%±1,127.66% and 888.10%± 988.52%, lateral gastrocnemius 650.72%±504.10% and 494.05%±363.58%, rectus femoris 785.53%±960.66% and 695.36%±989.98%, gluteus maximus 1,398.78%±2,730.48% and 930.33%±1,943.44%, and gluteus medius 1,201.03%± 3,745.77%, and 950.49%±3,257.50%, respectively, showing a significant difference between the two walking tasks (
The walking speed was slower during walking while using a smartphone (10.15±1.29 sec) than that during normal walking without using a smartphone (8.92±1.10 sec) (
The cervical flexion angle was greater during walking while using a smartphone (30.79°±8.63°) than that during normal walking without using a smartphone (4.27°±3.28°) (
The study aims to determine the effects of smartphone use on the lower extremity muscle activity during walking. Our results show that the participants walked with less muscle activity in the gluteus maximus and medius, biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior when using a smartphone compared to when walking without using a smartphone. Researchers found that the vasti, hamstring, gluteus maximus and medius, soleus, gastrocnemius, and dorsiflexors were the central factors of the fore-aft and vertical ground reaction force or the center of mass accelerations while walking (
Previous studies analyzed that the hip and knee extensor muscles provide much of the support in the first half of the stance phase (
In the human body, the gluteus maximus is the largest muscle (
During human walking, the tibialis anterior absorbs energy across the ankle joint as the foot comes in contact with the ground, producing force during the ankle plantar flexes (
Our study results showed that contrary to the gastrocnemius, the soleus muscle more while walking using a smartphone than in normal walking without using a smartphone, but not statistically significant. There is sufficient evidence showing that decreased medial gastrocnemius force generation would require an increase in soleus activation to maintain enough ankle joint torque (
Our results showed that the cervical flexion angles were 4.27° and 30.79° for walking without using smartphone and walking while using a smartphone, respectively, with a significant difference between the two tasks. This finding was consistent with the earlier result, where the mean cervical flexion angle was 38.5° for walking while texting on a smartphone. They reported that the use of a smartphone while walking poses potential risks for neck musculoskeletal problems due to a large neck flexion (
A recent study found that healthy young individuals walked with more thoracic kyphosis and lumbar lordosis when using a smartphone compared to when walking without using a smartphone (
There are some limitations to be noted. First, the participants of this study only walked for a short distance in a controlled laboratory space under controlled walking conditions. Second, we only evaluated young students in their 20s and not all ages. Third, the sample size of this study was too small for generalization. Future study should include enough walking distance and many people to cover various situations of smartphone use.
No potential conflict of interest relevant to this article was reported.
The authors received no financial support for this article.
General characteristics of the subjects (n=23)
Variable | Value |
---|---|
Age (yr) | 24.51±2.68 |
Height (cm) | 169.10±8.73 |
Weight (kg) | 70.28±13.54 |
Gender, male:femal | 14:9 |
Duration of use of the smartphone per day (min) | 329.13±61.92 |
Values are presented as mean±standard deviation or number.
Electrode location descriptions on the muscle
Muscle | Electrode location |
---|---|
Gluteus maximus | At 50% on the line between the sacral vertebrae and the greater trochanter |
Gluteus medius | At 50% on the line from the crista iliaca to the trochanter |
Biceps femoris | At 50% on the line between the ischial tuberosity and the lateral epicondyle of the tibia |
Rectus femoris | At 50% on the line from the anterior spina iliaca superior to the superior part of the patella |
Gastrocnemius (medial) | On the most prominent bulge of the muscle |
Gastrocnemius (lateral) | At 1/3 of the line between the head of the fibula and the heel |
Tibialis anterior | At 1/3 on the line between the tip of the fibula and the tip of the medial malleolus |
Soleus | At 2/3 of the line between the medial condylis of the femur to the medial malleolus |
Comparison of muscle activity
Muscle (%RVC) | Normal walking without using a smartphone | Walking while using a smartphone | |
---|---|---|---|
Tibialis anterior | 689.07±441.75 | 595.08±400.86 | 0.01 |
Soleus | 1,704.35±5,863.38 | 1,973.00±7,461.34 | 0.06 |
Gastrocnemius (medial) | 1,040.37±1,127.66 | 888.10±988.52 | 0.01 |
Gastrocnemius (lateral) | 650.72±504.10 | 494.05±363.58 | 0.00 |
Rectus femoris | 785.53±960.66 | 695.36±989.98 | 0.00 |
Biceps femoris | 1,906.61±3,444.23 | 1,455.29±2,315.15 | 0.06 |
Gluteus maximus | 1,398.78±2,730.48 | 930.33±1,943.44 | 0.01 |
Gluteus medius | 1,201.03±3,745.77 | 950.49±3,257.50 | 0.00 |
Values are presented as mean±standard deviation.
RVC, reference voluntary contraction.
Comparison of the 10-meter walk test
Index | Normal walking without using a smartphone | Walking while using a smartphone | |
---|---|---|---|
Speed (sec) | 8.92±1.10 | 10.15±1.29 | 0.00 |
Values are presented as mean±standard deviation.
Comparison of the cervical angle
Index | Normal walking without using a smartphone | Walking while using a smartphone | |
---|---|---|---|
Cervical flexion angle (°) | 4.27±3.28 | 30.79±8.63 | 0.00 |
Values are presented as mean±standard deviation.