Research Bites Vol. 3
Welcome back for another installment of Research Bites! For all of you who missed my research posts on my Instagram (@science_of_falling), you came to the right place. Every few weeks I will be posting a new set of five quick and dirty research reviews with the main findings, how it was performed, and my quick take on it.
The trick is, I only have the space of an Instagram caption (2200 characters) to dive in and extract main points. It makes for a fun challenge! If you want to see these posts sooner, head on over to Instagram and hit that follow button.
Enjoy that tasty research!
A study entitled, "Martial Arts Fall Techniques Reduce Hip Impact Forces in Naive Subjects After a Brief Period of Training" by Weerdesteyn, et. al. set out to see if inexperienced subjects could reduce hip impact after only 30 mins of training.
Study Details
🔸Subjects: 10 women; Age 28 +/- 6.6y; weight 65 +/- 6.6kg; all inexperienced fallers
🔸Underwent 30 mins of martial arts fall training before data collection
↪sideways martial arts falls on a mat from kneeling height
🔸Experimental procedure included two types of falls: sideways martial arts fall (MA) and block fall (falling down and abruptly stopping with the arm)
↪subjects fell onto force plate covered by a mat
↪ subjects initiated sideways fall and were given a single syllable verbal cue that signaled either the MA fall or block fall
↪2 series of 15 falls in random order were conducted
↪Fall kinematics taken by 6 camera system
↪hip impact velocity calculated based off camera imaging
Study Findings
🔹Compared to a block fall, MA falling techniques reduced hip impact force by ~16%
🔹Impact velocity with MA falls reduced by ~6.7%
My Take 🤔
I think this study really solidifies the idea that teaching patients to fall is an achievable and realistic goal for clinical practitioners. Considering that a 30 min training session (the length of a typical PT session) led to decreased hip impact forces during a fall, this study shows the potential clinical utility of the modality. In my opinion, it is almost a disservice not to teach patients this potential injury reduction tool. Of course, it is important to note this was done on younger subjects, but that is no reason to think this could not apply to older subjects with no comorbidities.
A study by Martins, et. al. in 2020 set out to determine how unilateral hip abductor fatigue would affect balance and functional tasks in elderly women.
Study Details
🔸100 healthy women; Ages 60-75yo (mean age 66.2yo)
🔸Underwent three tests before and after undergoing a fatigue protocol for their dominant leg hip abductors
🔸Fatigue protocol performed on a Biodex Isokinetic Dynamometer; 3 rounds of max effort pushes into abduction (each round followed by a functional test); hip abduction set at 60deg with a total amplitude of 30deg; researches had participants push until a Modified BORG score reached of 9-10/10
🔸Functional testing consisted of single leg balance (SLB), maximum gait speed (MGS), and Step Test (ST)
🔸All functional test performed in random order during pre and post testing
Study Findings
🔹Pre/post testing of single leg balance resulted in a mean drop of 28.1% in balance ability during the SLB test (Pre: mean 20.7s; Post: 14.9s)
🔹Pre/post testing of the MGS test resulted in a mean drop of 5.3% (Pre: 1.8 m/s; Post: 1.7 m/s)
🔹Pre/post testing of the ST resulted in a mean drop of 2.3% (Pre: 43.5 cm; Post: 42.5cm)
My Take 🤔
Clearly, as seen in this study, maximally fatiguing the hip abductor affects pure single leg balance ability. Interestingly though, despite this clear finding during the SLB the same was not significantly true to a large degree during the MGS or ST. In these more functional movement task the hip abductor fatigue was not shown as a huge detriment. This may be due to the body's ability to compensate with other muscles to maintain functional capacity. But, this study only looked at gait speed and stepping height ability. It would be interesting to see what the quality of gait and stepping was in conjunction with the pure data. Overall, this may be an important study in those who require high levels of balance such as in board sports or pure balance sports, but not so much in more locomotive sports such as soccer or basketball.
A study by Nakagawa et. al. in 2018 set out to find if passive hip internal rotation (IR) range of motion (ROM), ankle dorsiflexion (DF) ROM, and trunk muscular endurance affected knee valgus during a single leg squat and functional performance during dynamic balance testing.
Study Details
🔸121 Brazilian military recruits;mean age 18.43 years; mean weight 66.63 kg; mean height 1.71m
🔸 All injury free for at least 6 months with no prior lower extremity surgeries or injury
🔸Underwent passive hip IR ROM testing in prone on table, weight bearing ankle ROM testing in a lunge position, and trunk endurance testing in three position to test anterior/lateral/posterior endurance (plank, trunk extensor endurance test, side plank respectively)
↪Endurance testing performed and timed in the aforementioned positions until perfect form was broken
🔸Single leg squat performed by subjects 3 times at a rate of 15 squats/min to depth of 60 degs while being recorded by digital camcorder to assess knee valgus angle
↪Angle of knee valgus taken at maximal flexion depth
🔸Subjects additionally underwent the Y-Balance Test in the anterior, posterolateral, and posteromedial directions.
↪Performed barefoot with 6 practice trials and 3 testing trials
↪Reach distance averaged and normalized to a % of the subjects leg length
Study Findings
🔹After testing, it was found that decreased hip IR ROM in conjunction with having increased DF ROM correlated with less knee valgus during the single leg squat
🔹Performance in the anterior direction on the Y-Balance Test was better in those with more DF ROM
🔹Performance in the posterolateral and posteromedial directions on the Y-Balance Test was better in those with higher trunk extensor endurance scores
My Take 🤔
This study seemed more like two studies in one which is pretty cool. Although all subject were young Brazilian males, the findings show how important ankle DF ROM is to lower extremity function and control. More seems to be better overall. Also, its interesting that trunk extensor endurance plays a role in posterior balance ability. This may be partly why many people with low back pain also have balance deficits.
A systematic literature review and meta-analysis by Lesinski et. al. in 2014 set out to discover what current research says about proper dosing of balance exercise for improved balance ability.
Study Details
🔸Initially started with 596 articles from the years 1984-2014 that all related to balance training in healthy young adults. Sourced from PubMed, Web of Knowledge, and SPORTDiscus
🔸Final analysis included only 25 studies (Mean PEDro score of 5 [fair]) that met inclusion criteria of 16-40 yo participants, at least one behavioral balance performance outcome measure performed, and were a randomized controlled study.
🔸Within-subject effect size (ESdw) and between-subject effect sizes (ESdb) calculated
🔸Studies included information on training status of participants, training modalities (frequency/volume/training period), and type of balance outcomes (steady-state [SS], proactive [PA], and reactive)
Study Findings
🔹Mean ESdb showed balance training was effective to increase balance ability
🔹Elite athletes showed larger effect sizes (gains) with SS and PA than other groups
🔹Dose-response findings found balance training of 11-12 weeks, 3-6x/week, 16-19 total sessions, 11-15min/session, 4 exercises/session, 2 sets/exercise, and 21-40s/set are most effective to ⬆ SS balance ability
🔹Due to small # of studies, proactive and reactive balance findings could not be qualified
My Take 🤔
This is the first article of its kind to lay out a balance improvement formula. Although the study quality was not high based off PEDro score, this is the best we have at this time in regards to a science backed balance program structure.
I found it really intriguing that elite athletes made greater balance improvements than thier less athletic counterparts. Often this is not the case. This may be due to their greater ability to adapt to motor challenges. My main takeaway is that a small amount of consistent balance exercise can most definitely improve balance ability! Not only that, but now trainers and clinicians have a formula to follow.
Research conducted by Bakker et. al. in 2021, set out to find what the effects of specific balance training were on overall balance skill acquisition, retention, transferability, and neural plasticity.
Study Details
🔸36 healthy young adults: age 20.9 +/- 1.9yo, height 1.8 +/- 0.1m, mass 69.5 +/- 8.2 kg
🔸Participants randomly assigned to 3 groups: Balance specific training (BT), Non-balance specific training (CT), Non-active control (NT)
↪BT Group: used .4m wobble board with feet placed .2m apart; underwent 3 blocks of 8 sets of 45s long balance trials, each block separated by 5 min rest, each set followed by 30s rest
↪CT Group: used bicycle ergometer at rate of perceived exertion of 12-13; 4 sets of 5 mins with 2 min rest in between
↪NT Group: Sat at table reading or watching TV
🔸Single training session
🔸Pre-test, immediate post-test, and 7 days later (retention test) after testing wobble board balance, static balance, dynamic balance tasks were assessed, transcranial magnetic brain stimulation (TMS) performed to assess neural plastic changes, and analyzation of intermuscular coherence of recorded muscular activity assessed
Study Findings
🔹Groups did not differ significantly at pre-test
🔹Wobble board balance ⬆ 207% in BT group, but no significant change in other groups
🔹Improvements retained (although degraded) after 7 days off from training
🔹Wobble board balance improvements did not transfer to static/dynamic balance tasks
🔹No significant findings with TMS or EMG in any group
My Take 🤔
Whoa...there was a lot going on in this study! So much in fact that I had to delete some of the testing details to fit this post on Instagram. What this study really boiled down to was that balance training can improve drastically after one session BUT needs to be task specific. At very least, balance training should be extremely variable if the aim is overall balance improvement. Good news is, gains from a single training session can be dramatic and stick around for awhile.
Thanks for reading the third volume of Research Bites! I hope you learned a tidbit or two. Be sure to follow my Instagram account to see these research bites right away, and comment below on what you think about the findings above.
Happy Falling!
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