The effects of 90-degree training and full range training on common knee pain

The effects of 90-degree training and full range training on common knee pain

¹Sriharsha Jaladhi- primary author/lead researcher, ²Sruthi Anne, ³Suresh Vellanki- mentor

¹We Strive, Green Hope High School, Cary, North Carolina

²We Strive, Green Hope High School, Cary, North Carolina

³We Strive, Cary, North Carolina

Student Authors

Sriharsha Jaladhi (high school), Sruthi Anne (high school)

SUMMARY

Throughout the years, it was widely believed that strength training involving that knee that exceeded angles of 90 degrees increased pain and injury risk in the knee. More recently, studies are finding that training through a full range of motion may be beneficial for the knee and can reduce pain. This causes debate on whether one style of training may be better than the other in terms of reducing knee pain. The purpose of this study was to try to find if one style of strength training was better than the other at reducing knee pain. If strength training reduces knee pain, then strength training through a greater range of motion may reduce knee pain more effectively. Two programs were created using similar exercise structures that incorporated the two different styles of training. Two participants with similar knee pain and profiles were placed on each program and data was collected at the end of each week. At the end of the study period, the participant on the full range of motion program saw his pain levels decrease 50% from the initial data point while the participant on the 90-degree program saw a 20% decrease in pain. (Bar graph 1) These results support the claim that training through a full range of motion may be more effective at reducing knee pain than stopping at 90 degrees. This may suggest that in the future, more full range exercises may be used in physical therapy sessions to reduce knee pain.

INTRODUCTION

Knee pain is something many people struggle with, especially those who live active lifestyles. Figuring out how to confront knee pain and get rid of it is possibly an even bigger struggle. Research has shown us that exercise is beneficial for people with knee pain.₁ The challenge in this, however, is figuring out which exercises are better to reduce knee pain than others. In recent years, we have seen debates over whether one should look to train their knee through a full range of motion or only train through a 90 degree range of motion.₂ Proponents of 90 degree training say that going past 90 degrees while training can result in injury.₃ advocates for full range training say that injuries occur because we don’t do strength training through a full range of motion.₄ Both paths have led many people to reduce their knee pain so this prompts a question; which form of training is better?

RESULTS

After two weeks on their respective programs, the participant on the 90-degree program saw no changes in his pain levels. He also observed no differences in how his legs were feeling. The only change he reported was increased ankle mobility. The participant on the full range program reported that his pain level had dropped from a 6 to 4 and that his legs felt stronger and more stable. He also reported that his quadriceps and patella tendons felt stiffer than before. Lastly, he reported that he noticed increased mobility in his hips, knees, and ankles. After four weeks, which was exactly halfway through the program, the participant on the 90-degree program reported that his pain levels had dropped from a 5 to a 4 on the 10-point scale. He observed that he had increased mobility in his knees and ankles while he observed no change in hip mobility and strength in his legs. The participant on the full range program reported that his pain level dropped from a 4 to a 3. He reported that his legs felt stronger and more stable and observed increased mobility in ankles, knees, and hips. After six weeks, the participant who was on the 90-degree program reported that his pain had increased slightly that week. He reported that his pain went from a 4 to a 5. He continued feeling stronger and more stable in his legs and experienced improved mobility in his ankles, knees, and hips. The participant on the full range program reported that his pain dropped from a 3 to a 2. He also observed that his legs felt stronger and stable while noticing significant improvement in ankle, knee, and hip mobility. After eight weeks, which was the end of the program, the participant on the 90-degree program reported that his pain levels had dropped from a 5 to a 3. He reported that his legs felt stronger and more stable and reported increased knee and ankle mobility. He observed no changes in his hip mobility. The participant on the full range program reported that his pain levels had dropped from a 2 to a 1. He observed that his legs felt stronger and more stable as well as noticing significantly improved mobility in his ankles, knees, and hips.

Discussion

Over the course of the study, the participant on the 90-degree program saw his pain decrease from a 5 to a 3 on a ten-point scale while the participant on the full range program saw his pain decrease from a 6 to a 1. These results could indicate that progressing through a full range of motion exercises in the knees combined with mobility work may be more efficient at reducing knee pain rather than a more traditional, 90-degree range of motion exercises combined with mobility work. This could be because training in a full range of motion prepares the body to handle daily movements better than limiting training at 90 degrees. For example, a daily movement such as going down the stairs is roughly the same type of motion as the Poliquin split squat. The KOT squat involves a similar motion and shin angle to running and sprinting. The eccentric pistol squat had a similar movement to sitting down or getting up from a chair. The 90-degree program however, had exercises that don’t exactly involve any movements that one may find on a day-to-day basis.

This could be a possible explanation on why the full range exercises seemed to provide a greater decrease in pain. Training movements that one sees very frequently may be more effective at reducing pain. Another interesting factor was the ankle, hip, and knee mobility of the participants. The participant on the full range program reported a higher increase in mobility compared to the participant on the 90-degree program. This can likely be attributed to the fact that the full range program had exercises that required greater ranges of motion which can increase the mobility of the joints and build strength through the range of motion more effectively than the 90-degree program. So, if one ever struggles with knee pain, exercising through a progressed full range of motion may potentially reduce knee pain noticeably. More research will be required to support this finding in the future. A similar study may be conducted with at least 30 participants on each program representing the general population placed in each group to further investigate these findings.

MATERIALS AND METHODS

For this study we decided to do a comparison study between two participants of similar background and profile. Two programs were designed incorporating some of the best and most popular bodyweight exercises. One program was designed using 90-degree exercises and the other using full range exercises. Both programs had workouts for six days a week for eight weeks. The structure of each program was the same. Day 1 and 5 were the main workouts which focused directly on strengthening the knee.₅ They started off with a dynamic warm up followed by two compound movements which are exercises that use multiple muscle groups at the same time, a knee specific strength exercise, an eccentric exercise which focused on increasing load tolerance of the knee, and some static stretches.₆ Day 3 had a different workout which focused more on strengthening surrounding muscle groups to give the main muscle groups time to recover. This workout started off with a dynamic warm up, some isometrics, and accessory work to strengthen the hamstrings, glutes, calves, and tibialis and ended with static stretches. Day 2, 4, and 6 were all mobility days which were the same for both programs. These days had short mobility exercises focused on improving range of motion in the hips, knees, and ankles.₇ Participants were provided video demonstrations of every exercise. Reference table 1 and table 2 for the full range and 90-degree programs respectively.

REFERENCES

1. Lindberg, Sara. “10 Visuals of Exercises to Help Relieve Knee Pain.” Healthline, Healthline Media, 13 Dec. 2019, https://www.healthline.com/health/exercises-for-knee-pain#strengthening-exercises.

2. Kiely, Nathan. “Knees-over-Toes: Cutting through the Hype.” Sportsmith, 21 June 2022, https://www.sportsmith.co/articles/knees-over-toes/.

3. Michael Lau PT, DPT. “Knees over Toes - Is It Safe?” [P]Rehab, 8 Sept. 2022, https://theprehabguys.com/knees-over-toes-is-it-safe/.

4. An exercise physiologist and faculty, Fabio. “Is It Ever Okay for Your Knees to Extend beyond Your Toes While Doing Squats or Lunges?” Can Your Knees Extend Beyond Your Toes When Squatting? | ACE Blog, https://www.acefitness.org/resources/everyone/blog/562/is-it-ever-okay-for-your-knees-to-extend-beyond-your-toes-while-doing-squats-or-lunges/#:~:text=It%20is%20a%20myth%2C%20however,the%20knee%20during%20a%20squat).

5. “9 Best Knee-Strengthening Exercises.” Bethesda Health Group, 24 June 2021, https://bethesdahealth.org/blog/2016/01/04/9-best-knee-strengthening-exercises/

6. Dunkin, Mary Anne. “11 Knee Pain DOS and Don'ts.” WebMD, WebMD, https://www.webmd.com/pain-management/knee-pain/knee-pain-dos-and-donts.

7.

Neta. “How Tight Hips Can Cause Knee Pain.” NETA, National Exercise Trainers Association, 17 May 2019, https://www.netafit.org/2019/04/how-tight-hips-can-cause-knee-pain/.

Figures and Figure Captions

Table 1

This table shows the exercises and structure of the full range program. Note that the warmups, static stretches, mobility routine, and the accessory workout for day three in both programs are the same.

Table 2

This table shows the exercises and structure of the 90-degree program. Note that the warmups, static stretches, mobility routine, and the accessory workout for day three in both programs are the same.

Bar Graph 1

This figure shows the reported pain levels of the participants throughout the course of 8 weeks. The full range participant reported a greater decrease in pain over the course of the study.