While exercise is an excellent tool for maintaining a healthy lifestyle, some forms of exercise could have hidden risks for patients with ocular hypertension and glaucoma. Others, on the contrary, may have an added benefit of IOP lowering.
This article will review the available literature on three common types of exercise (aerobic exercise, weight training, and yoga) to help you give the best, evidence-based advice to those patients whose IOP really matters.
How different types of exercise influence IOP
Aerobic (cardio)
Aerobic exercise, often called “cardio” because it gets the heart pumping and heart rate up, strengthens the major muscle group, and decreases risk factors for chronic diseases. including cardiovascular disease, hypertension, diabetes, and obesity. The resulting release of endorphins is even a mood booster.
Examples of aerobic exercise are:
- Running
- Brisk walking
- Biking
- Dancing
- Swimming
- Hiking
- Most sports (ex., football, baseball, basketball, soccer, volleyball, rugby)
Studies on the impact of aerobic exercise on IOP
Aerobic exercise of at least moderate level is recommended for 30 minutes, 5 times per week for adults.1 In addition to the whole-body benefits, aerobic exercise can also induce IOP lowering. Yuan et al. studied the heart rate, blood pressure, IOP, and Schlemm’s canal architecture in participants before and after 30 minutes of running on a treadmill at moderate-intensity speed.
Heart rate was tracked using a Fitbit Charge 2, IOP was measured by Goldmann applanation tonometry, blood pressure was measured using an Omron automatic cuff, and Schlemm’s canal architecture was captured using the CASIA Corneal/Anterior Segment SS-1000 OCT and ultrasound biomicroscopy.2
When compared with baseline, healthy subjects and those with a diagnosis of primary open-angle glaucoma (POAG) experienced significant IOP lowering after aerobic exercise. The average cross-sectional area and dimension of Schlemm’s canal were significantly increased in both groups after the exercise period.2
Interestingly, the extent of Schlemm’s canal expansion was less for the POAG subjects despite this group having a greater IOP lowering effect. No difference was found among subjects of the POAG group based on their IOP-lowering treatment history. The study did not determine how long the IOP lowering lasted after exercising.2
The IOP-lowering effect of exercise in healthy patients
The work of Stanescu et al. provides further evidence to support the benefit of aerobic exercise on IOP. Over 17,000 subjects without diabetes or cardiovascular disease (as determined by a physical exam) received IOP measurement and physical fitness testing.3
IOP was measured using the HNT-7000 non-contact tonometer and was re-checked by Goldmann applanation if equal to or greater than 21mmHg. Cardiovascular fitness testing was performed according to the Bruce protocol (a standardized treadmill test), and subjects were grouped by level of fitness.3
This study did not test IOP pre- and post-exercise but correlated cardiovascular fitness with IOP. The subjects with the lowest level of fitness were 2.2 times more likely to have elevated IOP when compared to the other groups.
Even after accounting for other known cardiovascular risk factors (like smoking, high cholesterol, and weight), having a low level of cardiovascular fitness was associated with a 90% increased likelihood of IOP at or above 21mmHg in at least one eye.3
Weight lifting
Lifting heavy weight loads has been observed to cause an acute, drastic increase in IOP. To investigate this in the context of weight-lifting exercise, a study by Vera et al. monitored IOP in 26 healthy subjects while they performed isometric squats holding varying weight loads.4
The participants lifted three different weight loads, which were low, medium, and high, relative to their maximum capacity (they were also asked to avoid the Valsalva maneuver during testing). An iCare rebound tonometer was used to measure IOP before, every 6 seconds during a 1-minute exercise, and then 10 seconds after each exercise.4
IOP increases were observed for all of the weight load levels, with the IOP increasing linearly with increased time maintaining the squat position. The greatest overall IOP increase occurred when the participants performed squats with the heaviest load and at the 60-second mark.4
The mean baseline IOP of the subjects was 16mmHg. The average IOP increase measured at 60 seconds was 5mmHg for the low-load exercise, 7mmHg for the medium-load exercise, and 9mmHg for the high-load exercise. The IOP increase was only temporary and returned to a comparable baseline by 10 seconds after the exercise.4
Transient IOP increases due to weight lifting
Bench press weight lifting also causes a transient increase in IOP. Vieira et al. studied 30 healthy subjects performing a bench press at 80% of their maximum ability. The Tono-Pen XL was used to measure IOP.
The subjects performed four repetitions with normal breathing followed by a final repetition where they were asked to hold their breath momentarily while holding up the barbell (“mode 1”) and four repetitions with normal breathing and continuing to exhale while lifting the barbell on the last repetition (“mode 2”).5
IOP measurements were taken during each in addition to before and after the exercise regimen. The subjects’ right eyes were measured for mode 1 and left eyes for mode 2. Results showed that 90% of subjects had an IOP increase with mode 1 and 62% with mode 2.5
Further, 30% of subjects had an IOP increase >5mmHg while completing mode 1 versus 21% while completing mode 2; and two subjects in mode 1 experienced an IOP increase of >10mmHg while none in mode 2 experienced such a large IOP increase.5
Yoga
Yoga is a calming practice that can clear the mind and improve flexibility, but certain poses, particularly any with the head positioned downward or the body over the head, can cause a temporary and rapid increase in IOP. Yoga poses involving head-down or body-over-head cause an increase in hydrostatic pressure.
This results in increased episcleral and orbital venous pressure, which causes an increase in IOP.6 Additionally, being in an inverted position causes a thickened choroid, reduced choroidal blood flow, and narrowing of the anterior chamber, which can increase the risk of angle closure.7
Studies on the impact of yoga on IOP
Jasien et al. measured IOP in subjects before, during, and 2 minutes after four common yoga poses. The Reichert Model 30 pneumatonometer was used. Downward dog pose (Adho Mukha Svanasana) induced the largest IOP increase, followed by the standing forward bend (Uttanasana), plow pose (Halasana), and legs-up the wall pose (Karani), respectively.8
A summary of the results can be seen in Table 1. The increase in IOP occurred within 1 minute of the subject assuming the pose and returned to the baseline measurement within 2 minutes after the pose was broken and the subject took a seated, resting position.8
| Yoga Pose | IOP Change in Glaucoma Patients | IOP Change in Non-Glaucoma Patients |
|---|---|---|
| Downward dog | 17 ± 3.2mmHg to 28 ± 3.8mmHg | 17 ± 2.8mmHg to 29 ± 3.9mmHg |
| Standing forward bend | 17 ± 3.9mmHg to 27 ± 3.4mmHg | 18 ± 2.5mmHg to 26 ± 3.6mmHg |
| Plow | 18 ± 2.8mmHg to 24 ± 3.5mmHg | 18 ± 2.7mmHg to 22 ± 3.4mmHg |
| Legs-up-the-wall | 17 ± 4mmHg to 21 ± 3.6mmHg | 17 ± 2.8mmHg to 21 ± 2.4mmHg |
Table 1: Courtesy of Jasien et al.
Shajiei et al. performed a similar study of IOP in the same four yoga poses, finding comparable results. The researchers measured IOP with the iCare HOME2 Tonometer before, during, and after assuming each of the yoga positions for 90 seconds.9 The findings from this study are listed below in Table 2.
| Yoga Pose | IOP Change in Glaucoma Patients | IOP Change in Non-Glaucoma Patients |
|---|---|---|
| Downward dog | Increase by mean of 15.1 ± 4.44mmHg | Increase by mean of 16.5 ± 3.71mmHg |
| Standing forward bend | Increase by mean of 11.6 ± 3.86mmHg | Increase by mean of 14.4 ± 4.48mmHg |
| Plow | Increase by mean of 6.0 ± 2.24mmHg | Increase by mean of 7.5 ± 4.21mmHg |
| Legs-up-the-wall | Increase by mean of 2.8 ± 2.8 mmHg | Increase by mean of 1.6 ± 1.42mmHg |
Table 2: Courtesy of Shajiei et al.
Those who practice yoga regularly could be at risk for glaucomatous optic neuropathy from the IOP spikes. Gallardo et al. presented a patient who practiced daily yoga for many years, including significant time spent in the Sirsasana, or headstand, pose.10
This is the ultimate “head-down” posture and ultimately led to progressive optic neuropathy and visual field loss for the patient over the course of 2 years.10 Baskaran et al. also studied IOP in the Sirsasana pose and found that the baseline IOP doubled once the subject entered the yoga pose.11
Key takeaways
Exercise can improve one’s strength, endurance, self-discipline, and overall health. It can also reduce stress and improve mental wellness.
The evidence supports that IOP-lowering can be added to the list of many health benefits of aerobic exercise (cardio), but certain yoga positions and weight-lifting exercises should be performed with caution in those patients where increased IOP would be detrimental.
While longer-term studies on the impact of inverted yoga poses and weight-lifting exercises on glaucoma progression are needed, we know that any IOP spikes can lead to glaucomatous optic nerve damage and, therefore, should be avoided when possible.
For at-risk patients, a questionnaire about modifiable risk factors could prompt this conversation. Educating patients on the current evidence and risks/benefits can help them to find the right exercise regimen that also protects their ocular health.
