I have struggled over the years as to the importance of including toe flexor strengthening as part of a program for plantar fasciitis. Many researches agree that the potential causes of plantar fasciitis are just too numerous and multi-factorial. The evidence in the literature has not been conclusive and I have let many of my patient’s comments that “this is silly” when picking up marbles dictate my decision-making. I have slowly but surely, and I believe wrongly, eliminated this important exercise from my treatment approach. I have recently read several articles that have rekindled my enthusiasm for toe flexor strengthening. So why the change in heart??
I am always looking for ways to get our patients better…faster. I have written a book on plantar fasciitis called the Plantar Fasciitis Treatment Manual and it identifies ankle muscle weakness as a result of plantar fasciitis but not include the presence of toe flexor weakness. That is my oversight and I will correct that in the book. Yes, the literature does identify weakness of the ankle muscles and the toes flexor muscles with the plantar fasciits population, yet the research does NOT confirm any causative factor of this weakness on the development of plantar fasciitis.(1,3,4) It is the chicken or the egg conundrum. Unfortunately, there are theoretical assertions that the “flexor digitorum brevis muscle (the muscle directly underneath the plantar fascia) plays an important role in distributing pressure away from the plantar fascia” that are simply not supported by research. (2) Does this mean that we should not perform strengthening exercises? Let me provide some more evidence.
As we get older, we get weaker. We all lose muscle mass, we lose muscle fibers and, as a consequence, we see decreases in strength between the ages of 30 and 80 within a range of 20-40%.(5) Several articles have also shown that “older people” exhibit 24-40% less strength in the muscles of the foot and ankle(5,6,7,8). As a consequence of foot and ankle weakness, older adults are more susceptible to loss of balance, the development of foot and toe deformities and can be susceptible to overuse syndromes such as plantar fasciitis. (5,6,7,8) The biggest question that has not been answered when it comes to strengthening exercises for older adults is WHICH exercises are the most effective?
As a result, we have to rely on some common sense. If the muscles in our ankles and feet get weaker as we get older (proven!), then we should strengthen them to avoid plantar fasciitis. Right? Not necessarily. There is not a direct correlation between weakness and the development of plantar fasciitis but, then again, many people don’t believe that there is a direct correlation between human activity and climate change. My point is why should we wait to change our approach until it is conclusive – whether it be climate change or your plantar fasciitis?
(Courtesy of Freedigitalphotos.net)
CROSS FIT 101
First of all, you need to understand the difference between aerobic and anaerobic exercise. Aerobic exercise requires oxygen, is low powered and lasts for greater than 15-20 minutes. Anaerobic exercise, like Cross Fit, does not require oxygen, is high powered and each exercise lasts less than 2 minutes.
The Positives: Recent studies have shown that anaerobic exercise is a vastly superior protocol for fat burning than it’s less intense aerobic counterpart. There is evidence that shows that anaerobic exercise is evenly matched to aerobic exercise with regard to cardiovascular benefits. Check out the evidence in an article in the Journal of Strength and Conditioning. More evidence that comparable calorie burning effects can be achieved in half the time with anaerobic exercise.
The Negatives: Potential for INJURY! The article in the Journal of Strength and Conditioning also states that 16% of the participants dropped out due to “injury or overuse”. In addition, in 2011, the U.S. military, in conjunction with the American College of Sorts Medicine, advised soldiers to avoid CrossFit, citing “disproportionate musculo-skeletal injury risk.” You can read it HERE. In 2009, the US Military was encouraging training programs such as CrossFit. You can read it HERE. So what happened?
CrossFit goes out of its way to warn people that if they can’t maintain proper technique, they should back off. After all, the CrossFit mantra is “Mechanics, Consistency, Intensity”. Backing off , however, is a hard sell for many participants because workouts are viewed as a competition. The 2009 US Military study states that “Properly trained coaches are fundamentally important in both establishing an effective training program and developing proper movement mechanics in athletes.” It sounds like something, or someone, went wrong between 2009 and 2011.
So I guess the biggest question that you should ask (before joining a local Cross Fit gym) is WHO is running the classes and HOW they are trained. Make sure they at least have Level I or Level II Cross Fit training. A power lifting background is very helpful as power lifters are obsessive about proper form. Make sure you observe a class or two to witness how or if the instructor is scrutinizing and ensuring proper form. The proof is in the puddin’.
I have created several videos to demonstrate HOW and WHY we make custom foot orthotics at WalkWell Foot Orthotics to treat various foot pain conditions. You can share the links to these videos with friends or family members who may be suffering from foot pain and who are looking for answers. The conditions I cover are:
1. Plantar Fasciitis
2. Metatarsalgia ( ball of foot pain )
3. Supinated or High Arch Foot
4. Specialized Foot Orthotics
5. Sesamoidits ( pain under big toe )
6. Posterior Tibialis Dysfunction ( pain on inside of ankle )
7. Hallux rigidus / Hallux Limitus ( Big Toe Pain )
Yes. We treat a lot of plantar fasciitis. There is a lot of foot pain out there. While performing a literature review of heel pain in 2005 (follow this link to READ MORE), I made reference to several articles about the prevalence of heel pain. One United States study estimated that one million patient visits each year are for the diagnosis and treatment of plantar heel pain. This disorder appears in the sedentary and geriatric population, it makes up one quarter of all foot injuries in runners, and is the reason for 8% of all injuries to people participating in sports. As many of you know, all that we do regarding foot orthotic fabrication and physical therapy is with good, evidence-based reason. I fabricate custom foot orthotics based on sound biomechanical principles and evidence-based research. Patients are always asking me “so how will foot orthotics help my plantar fasciitis?” Here is the answer! I have included both a clinical description as well as a more basic description in the video. This will allow you to refer your doctor and/or PT as well as a relative who may ask WHY or HOW we made your foot orthotics. I have included references for several articles that have had a profound influence on my treatment and fabrication philosophy regarding plantar fasciitis. I would like to share my insights with you.
It has been my experience that positive results can be achieved much more quickly for cases of plantar fasciitis using the combination of softer materials to cushion the foot in combination with stiffer, denser materials to redistribute pressures on the foot. My direct molding techniques produce a total contact orthotic which reduces weight bearing pressure on both the heel and forefoot. These findings for total contact orthoses have been confirmed by both Mueller et al10,11 and Ki et al12. As you can see from my samples on the video, I utilize softer materials as a top layer with the addition of a heel pad on the bottom. I reinforce the arch in order to redistribute pressures up against the talonavicular joint (or midfoot). I utilize a forefoot valgus post (higher on the outside of the forefoot) with a slight reverse Morton extension (ledge under toes 2-5) in order to plantar flex the first ray (big toe lower than the other four toes) and unload both the fascia and 1st MTP joint (big toe joint) As I tell my patients, the foot orthotic is only as good as the shoe you put around it. Our best results with the over-pronating foot are achieved via the combination of motion control shoes and custom orthoses.
In regards to prefabricated orthotics such as ALine, it is one-shape-fits-all and only utilizes rearfoot posting “to help align the leg from foot to hip” per the website. The concept of rearfoot posting for biomechanical control is a much debated topic in the literature. Forefoot modifications are not an option. It is also a very rigid material against a painful heel. It has been my experience that prefabs such as ALine or Powerstep are a good option for the younger, athletic patient.
Don’t forget, our custom foot orthotics range in price from $120 to $165. I direct mold, fabricate, educate and issue in one hour! All adjustments included. Our WalkWell guarantee since 1997!!
Research findings continued……
Research done by Kogler1,2,3 et al has been instrumental in determining the appropriate type of rearfoot and/or forefoot posting for foot orthotics for plantar fasciitis. Kogler showed that rearfoot posting had little effect on plantar fascia strain, forefoot varus posting increased the stress, and forefoot valgus posting actually decreased the strain. Kogler concluded that foot orthotics which raised the talonavicular joint and prevented dorsiflexion of the first ray were most effective in reducing the strain on the central band of the plantar fascia. I recently made orthotics for a patient who said her doctor issued bilateral heel lifts “to take the stress off of the fascia”. Kogler actually showed no change in plantar fascia strain using heel lifts. However, heel lifts have been shown by Trepman et al4 in 2000 to decrease the compressive forces in the tarsal tunnel. Benno Nigg5, a researcher in Canada, has also published over 200 articles on biomechanics. He has stated that based on his results, custom foot orthotics, on average, control only 2-3 degrees of motion. This would be his kinematic results, however, he has done a lot of enlightening research on the kinetic effects of foot orthotics. A little bedtime reading for you!
Paul Scherer6,7,DPM has published several articles on the effects of custom orthotics on the 1st MTP joint. The concept of maintaining the first ray in a plantar flexed position unloads both the 1st MTP joint as well as the plantar fascia. Howard Dananberg8,DPM has also written several articles on this topic. Doug Richie9,DPM has been a great resource for the evidence behind the treatment of plantar fasciitis as well as posterior tibialis dysfunction. You may have heard of the Richie brace. Dr Richie states that the “most effective foot orthotic for plantar fasciitis is one that hugs against the navicular and flares away from (or plantar flexes) the first ray.”
1.Kogler, G. F.; Solomonidis, S. E.; and Paul, J. P.: Biomechanics of longitudinal arch support mechanisms in foot orthoses and their effect on plantar aponeurosis strain. Clin. Biomech., 11: 243-252, 1996.
2.Kogler GF, Veer FB, Solomonidis SE, et al. The influence of medial and lateral placement of wedges on loading the plantar aponeurosis, An in vitro study. J Bone and Joint Surg Am. 81:1403-1413, 1999
3.Kogler GF, Veer FB, Verhulst SJ, Solomonidis SE, Paul JP.
The effect of heel elevation on strain within the plantar aponeurosis: in vitro study.
Foot Ankle Int. 2001 May;22(5):433-9.
4.Trepman E, Kadel NJ: Effect of foot and ankle position on tarsal tunnel compartment pressure. Foot Ankle Int 20(11):721, 2000
5.Nigg, B. Biomechanics of Sport Shoes. 2011
6.Scherer PR, Sanders J, Eldredge, DE, et al. Effect of functional foot orthoses on first metatarsophalangeal joint dorsiflexion in stance and gait. J Am Podiatr Med Assoc 2006;96(6):474-481.
7.Scherer,P. Recent Advances in Orthotic Therapy. 2011
8.Dananberg HJ. Functional hallux limitus and its relationship to gait efficiency. J Am Podiatr Med Assoc. 1986; 76(11):648-52
9.Richie,D. Offloading the plantar fascia: What you should know. Podiatry Today, Vol 18. Issue 11, Nov 2005.
10.Mueller MJ, Hastings M, Commean PK, et al. Forefoot structural predictors of plantar pressures during walking in people with diabetes and peripheral neuropathy. J Biomech 2003;36(7):1009-1017.
11.Mueller MJ, Lott DJ, Hastings MK, et al. Efficacy and mechanism of orthotic devices to unload metatarsal heads in people with diabetes and a history of plantar ulcers. Phys Ther 2006;86(6):833-842.
12.Ki SW, Leung AK, Li AN. Comparison of plantar pressure distribution patterns between foot orthoses provided by the CAD-CAM and foam impression methods. Prosthet Orthot Int 2008;32(3):356-362.
The sacroiliac or SI joint is the articulation between the bone at the base of the spine called the sacrum and the bones on both sides of the pelvis called the ilium. Refer to the picture below.
Over 22 years of physical therapy, I have treated many patients with low back and buttock pain who were diagnosed with an SI joint dysfunction. The difficulty with diagnosing an SI joint dysfunction is that the SI joint has no specific distribution pattern of pain. Pain directly over the SI joint does not necessarily mean that the joint itself is involved. SI joint pain can very often be referred pain from other structures such as the disc, nerve root, or facet joints of the lumbar spine. Many physical therapists or physicians attempt to diagnose an SI joint dysfunction through palpation of bony landmarks as well as assessment of SI joint mobility. There is only a very small amount of motion in the SI joint i.e. 2-3 mm or 2-3° of gliding or rotation thereby making an accurate diagnosis very difficult. In addition, evidence based research refutes the reliability and validity of accurately assessing bony landmarks and SI joint mobility. McGrath et al has published an article, entitled “Palpation of the sacroiliac joint: an anatomical and sensory challenge” in which the concept of SI joint palpation is scrutinized. Freburger and Riddle performed a literature review looking at our ability to perform SI joint motion testing. They found poor inter-tester reliability, low sensitivity, and low specificity in several commonly performed tests. Inter-rater reliability is essentially the ability for multiple practitioners to come to the same diagnostic conclusion. If you have multiple individuals perform the same test, the results should be the same. Riddle and Freburger in another study noted that the ability to detect positional faults of the SI joint also has poor reliability. At present, the only acceptable method of confirming or excluding a diagnosis of a symptomatic SI joint is a fluoroscope guided intra-articular anesthetic block ie an injection directly into the SI joint. (Laslett et al) So how can I, as your physical therapist, assist in the diagnosis of an SI joint dysfunction? The answer: SI joint provocation tests!
Two recent studies by Laslett et al and Van der Wurff et al have demonstrated that there isn’t just one key or ideal SI joint provocation test. However, by performing several tests together, you can increase your sensitivity and specificity of detecting an SI joint dysfunction. Both studies reported that the accuracy of detecting SI joint dysfunction is increased if least 3 of the 5 tests are positive. Furthermore, if all 5 tests are negative, you can likely look at structures other that the SI joint. Van der Wurff et al reported that if at least 3/5 of these tests were positive, there was 85% sensitivity and 79% specificity for detecting the SI joint as the source of pain. Interestingly, another study by Kokmeyer et al agreed with the previous findings, but also noted that the thigh trust test alone was almost as good at detecting SI joint dysfunction as the entire series performed together.
Combining the two studies, there are 5 provocation tests to perform when attempting to diagnose SI joint pain:
- Thigh thrust/Femoral Shear test
- SI Distraction Test
- SI Compression Test
- Gaenslen’s Test
- FABER / Patrick’s test
The following video will demonstrate these tests. I would like to thank Mike Reinold, PT for his blog information that was used to complete this explanation of SI Joint dysfunction. Check out the video below!!
CORRECTION: I would like to clarify the SI distraction test as described in Laslett. I believe that he considers the direct posterior shear of the innominates as a distractive force of the ilium away from the sacrum. I initially interpreted this test as a compression of the SI joint via a distraction of the ASIS’s. I guess it depends on HOW you apply the force to the ASIS’s. Also, the sidelying “compression” test needs to be performed in a straight, linear fashion as well in order to compress the SI joint. It is important to place a towel roll under the lumbar spine in women in order to prevent sidebending stress t the lumbar spine. In OMT, we use the sidelying position to “distract” the SI joint using more of a rotational force on the lateral edge of the ilium in order to “open up” and distract the SI to get a feel for joint play. As you can see, these tests are not definitive for exactly HOW they stress the joint but they are specific for a stressing maneuver TO the SI joint.
I would like to highlight one of the unique treatment techniques that we offer at OrthoWell. As many of you know, we spend a lot of quality time during our biomechanical evaluation trying to “figure things out”. This is the reason that several of our referring physicians call us “THINKERS”. We pride ourselves in determining your functional diagnosis. This diagnosis is what we use to develop your plan of care and to educate you in how to alleviate your pain or dysfunction. Many of our patients have seen several physicians or therapists before hearing about us. For this reason, we offer specialized evaluation and treatment services that our patients may not have heard of and that may be appropriate to alleviate symptoms that have been unresponsive to prior interventions. One of these is Nerve Mobilization or NeuroMobilization. So what is it?
What is NeuroMobilization?
NeuroMobilization or Nerve Mobilization is a technique that we utilize to treat nerves that may be adhered, irritated, or compressed. Many patients that have been unresponsive to other physical therapy and present with a chronic history of referred symptoms like pain, numbness, or tingling into the arms or legs may respond to NeuroMobilization. Every patient that presents with referred symptoms or pain that has been unresponsive to localized treatment receives a complete neural tension evaluation. Neural tension testing is a way for your therapist to determine the extent of nerve involvement. By mobilizing a nerve, we can determine, in combination with manual traction and sensitizing maneuvers, whether your pain is originating from the spine or the periphery.
We can then perform NeuroMobilization techniques utilizing controlled neural tension maneuvers to mobilize the nerve up and down. David Butler,PT, has been at the forefront of these techniques for over 20 years. Although we still do not completely understand the exact mechanism, he proposes that NeuroMobilization (what David Butler calls Neurodynamics) can accelerate nerve healing and quiet down what he calls an “altered impulse generating system (AIGs)”. These AIGs may respond to the oscillations of NeuroMobilization by enhancing circulatory exchange or ion transfer in and around the nerve. You can read more about the techniques and science in David Butler’s book The Sensitive Nervous System.
Here is a video that highlights a sciatic nerve tension test and Neuromobilization.
I cannot count the number of times over the past 22 years that patients have told me “I USED to have an arch, but not anymore”. Is it true that you can actually lose your arch as you get older? The answer: YES. So what happens? Many doctors attribute a loss of your medial arch height to a condition labled posterior tibialis tendon dysfunction or PTTD. Your posterior tibialis muscle lies deep under your calf and it’s tendon inserts into your midfoot. It is responsible for turning your ankle inwards and “reinforcing your arch height.”
PTTD typically presents as a progressive increase in tendonitis pain which can lead to partial or complete rupture. The loss of PTT integrity has been hypothesized to produce a gradual change in the alignment of your foot. However, recent evidence shows that a partially torn or ruptured PTT is NOT the definitive reason for an adult acquired flatfoot. Let me show you. A study by Yeap et al followed 17 patients who underwent a surgical transfer of the PTT to a different part of the midfoot in order to control a drop foot. At a 5 year follow-up, none of the patients had a clinical flatfoot deformity. In other words, “losing” the PTT tendon by attaching it to a different part of the foot did NOT cause a flat foot. In light of this one study, there is sufficient evidence to rebuke the PTT as the sole reason for an adult acquired flatfoot.
Another study by Deland et al attempted to produce an adult acquired flatfoot in cadaver models by cutting the PTT. This produced only a minimal drop in height. It wasn’t until they severed the ligaments and plantar fascia on the underside of the arch that a complete arch collapse was achieved. Researchers Chu and Myerson confirmed the results of this study as well. So the evidence is here. A major contributing factor to the loss of arch height as we age is the loss of ligamentous integrity in the foot.
Did you know that women are 3 times more likely to be diagnosed with PTTD? It is most frequently found in women in their 50’s. Although a definitive hormonal link has not been established, PTTD appears to peak during the perimenopausal period. An interesting study performed at USC in 2011 found that women with PTTD compared with a control group had significantly decreased endurance and strength of hip muscles. Strengthening your hips may help to strengthen your arch. More evidence that everything is connected!
Can you raise your arch by strengthening the muscles in your feet? Did you know that there are 18 muscles in the arch of your foot? What does the research tell us? In my previous article on running technique, I mentioned an article by Robbins who showed radiographic changes in arch height after runners ditched their shoes and started walking and/or running barefoot. This should be a very slow process, but many coaches and therapists advise walking barefoot on grass or sand as a starting point. Two other studies by Fiolkowski et al and Headlee et al also show that when muscles in the arch weaken, the arch falls.
So what, specifically, can you do about your fallen arches?
Number 1 : Custom Foot Orthotics. You need to control the pain and unload the injured structures first. We are attempting to control some of the mechanical imbalances by fabricating foot orthotics that “hug” your midfoot. We utilize both rearfoot and forefoot posting (angling of the orthotic) in combination with motion control shoes to control your excessive motion. For more severe cases, some research shows better control of the twisting or internal rotation of the leg using braces such as ankle-foot orthoses. The Richie Brace is one example.
Number 2: Exercise!! Yes, it is very important. The articles above prove it. In order to “raise” your arch height with exercise, you need to be very consistent and compliant with your program. I have mentioned HOW to exercise in a previous post. I want to emphasize that, if you have flat feet, your arches will fall every time you stand or take a step if you don’t train yourself to prevent it. This means using the appropriate intrinsic muscles in your arch in combination with active joint repositioning. If you can master this, you will be in a constant state of muscle retraining and joint stabilizing while bearing weight on your feet.
You could then add barefoot walking on grass or sand as an adjunct to your program. My next post will highlight the research on the muscle training effects of minimalist shoes such as the Nike Free. Stay Tuned! Now, check out my videos on foot intrinsic training and an effective hip strengthening exercise called Clams.
WOW!! We have been really busy here at OrthoWell. Thanks to you-our awesome patients!! I have been a little sidetracked from my blog posts recently as I am SURE all of you have noticed and have “sorely” missed. With the help of my incredible crew we attended (with our treatment tables and elbow grease) one 5K, one half marathon, and one health care exhibition during the month of May. In the meantime, I have been very focused on bringing new life and a new face to my website. How do you like the snazzy, new look of this newsletter? You can see on our homepage how easy we made it to quickly view our clinic’s specialties and the things that set us apart from other physical therapy clinics. You can see how much more personalized and descriptive we made the website by adding our OWN pictures. We all felt like movie stars during the photoshoot. I have never before seen Geoff smile so much!?! The OrthoWell miracles continue!! With this post, I would love to introduce, with eager anticipation, my NEW LOOK at www.orthowellpt.com Please take the time to LIKE US if you like what you see. I also included a few pictures: Megh’s first and victorious half marathon run and Geoff and I healing the wounded at the Gloucester Twin Lights Half Marathon.
So how important is resistance training? I have had the privilege of working with one of my peers, a fellow PT, and strength and conditioning specialist, Mike Stare from Spectrum Fitness in Beverly, both professionally as well as personally. Mike helped to redirect MY fitness program while I was recovering from my knee injuries 1.5 years ago. Mike is on top of his game from a fitness training standpoint. He has devoted a lot of time and resources in developing an evidence-based approach to fitness and weight loss in ALL age groups. You can see this for yourself at his website. It is important for clients in a fitness program as well as our patients in physical therapy at OrthoWell to understand HOW to strengthen muscles.
The physiological principle of “overload” is what makes the difference between strength gains and stagnation. Resistance training is hard work! I tell my patients “If it’s easy, then you’re doing something wrong!” Is it true that people will lose 5-10% of muscle strength in every decade of life after the age of 40? Studies have shown that people can retain 100% of their muscle mass and strength from age 40 through their 80s with exercise! (Wrobelski, A. et al. The Phys and Sports Med, Sept 2011) You can read more on the Anti-Aging movement at Mike’s BLOG as well.
However, during exercise, you need to challenge your muscles physiologically. You need to provide a “load” that goes “over” your muscles comfort zone. In order for a muscle (including the heart) to increase strength, it must be gradually stressed by working against a load greater than it is used to. So how do you do this? There are many books and magazines such as Muscle Fitness that advocate all kinds of strategies for maximizing strength and muscle mass. Strength gains can be accomplished by performing a one-repetition maximum as well as via the typical 10 rep set approach. My approach, with the fine-tuning of Mike, is to instruct my patients in 2-3 sets of 8-12 repetitions per exercise. The most important factors to consider are the utilization of proper technique in order to isolate the specific muscle as well as to use the idea of the “loss of technical form” as your maximum output point. By the time you reach the 8-12th rep you should be tiring and on the verge of a loss of technical form. You should not work to fatigue as this will compromise your technique and become a safety concern. Regarding the frequency of strengthening exercise, studies show that strength gains are maximized at a frequency of 2-3x per week. The American College of Sport Medicine (ACSM) recommends working out a MINIMUM of 2x per week at an intensity that is equal to 70-85 percent of your one rep maximum (maximum weight you can use for one rep) for 8-10 reps and 1-3 sets. A program that comprises repetitions over 12 is considered endurance training. For cardiovascular benefits, the ASCM recommends exercising for a frequency of 3-5 times per week, at an intensity equal to 60-85 percent of your maximum heart rate for a time of 20-60 minutes. Research has shown that you’ll get the same beneficial results by exercising at 50-60% of your maximum heart rate that you would get exercising at an intensity 80% of your maximum heart rate.
At OrthoWell, as part of your physical therapy, we get you started on a strengthening program that targets your problem area. Finding the right practitioner to design a complete, individualized fitness program can be a very rewarding thing and Spectrum Fitness is definitely one of our choices. As Mike points out, “If there is one thing to do to improve the quality of life as we age, strength training would be it.”
For our athletes and runners, don’t forget that strength training has been PROVEN to enhance athletic performance. Read the following to get the facts!
-A University of Alabama meta-analysis of the endurance training scientific literature revealed that 10 weeks of resistance training in trained distance runners improves running economy by 8-10%. For the mathematicians in the crowd, that’s about 20-24 minutes off a four-hour marathon – and likely more if you’re not a well-trained endurance athlete in the first place.
-French researchers found that the addition of two weight-training sessions per week for 14 weeks significantly increased maximal strength and running economy while maintaining peak power in triathletes. Meanwhile, the control group – which only did endurance training – gained no maximal strength or running economy, and their peak power actually decreased (who do you think would win that all-out sprint at the finish line?). And, interestingly, the combined endurance with resistance training group saw greater increases in VO2max over the course of the intervention.
-Scientists at the Research Institute for Olympic Sports at the University of Jyvaskyla in Finland found that replacing 32% of regular endurance training volume with explosive resistance training for nine weeks improved 5km times, running economy, VO2max, maximal 20m speed, and performance on a 5-jump test. With the exception of VO2max, none of these measures improved in the control group that just did endurance training. How do you think they felt knowing that a good 1/3 of their entire training volume was largely unnecessary, and would have been better spent on other initiatives?
-University of Illinois researchers found that addition of three resistance training sessions for ten weeks improved short-term endurance performance by 11% and 13% during cycling and running, respectively. Additionally, the researchers noted that “long-term cycling to exhaustion at 80% VO2max increased from 71 to 85 min after the addition of strength training”