The Power Of Rereading Your Old Books

Picture by Tom Morris

I have always like reading. The Five Find Outers, The Famous Five, Moonface and The Faraway Tree  by Enid Blyton were my favorites when I was growing up. 

When competing in cross country/ track and field and triathlon, I pored over race reports, scientific articles on training, and sports biographies to help my athletic performance.

I also have this habit of rereading the books I like. Some books I've even reread a few times. I've realized that the older and wiser version of myself reads, analyses and understands things differently (and better) than the younger me.

The same applies to treatment and rehabilitation. Everyone seems enarmored with new treatment strategies, answers and solutions. Always looking for the latest flavor of the month.

Of course I do keep up with the latest updates. But do they always work better? Perhaps if we reread our older books/ articles we can better understand things we have have tried, considered or perhaps even ignored previously. You may find that most of the answers are already there. 

My family and I are currently away traveling, hence the short post this week. I am taking the time to read both old and new books. I love the feeling of paper between my fingers.

Have a safe holiday if you are traveling.

Anterior Pelvic Tilt

Picture of APT on the left by Oliver Ludwig

I had a patient come in this week saying he was told by another physiotherapist that he had an anterior pelvic tilt (APT) that was causing his low back pain. 

He was told that his poor posture while sitting for long hours caused it. Sitting for long hours is often thought to shorten the hip flexors while also weakening the core. There is no evidence that prolonged sitting causes APT. Some correlations were reported but lack consistency between left and right sides (Elliot et al, 2021).

However, even after being 'corrected' for his APT, his low back pain did not go away.

Many people will present in our clinic with a pelvic tilt. An article from Manual Therapy found that 85 percent of males and 75 percent of females (from 120 subjects) presented with an APT without any pain or disability. 6 percent of males and 7 percent of females presented with a posterior pelvic tilt without pain or disability too. So is APT really a dysfunction or is it normal?

There are also no agreement or guidelines as to what is too much or too little pelvic tilt. Moreover there is also no reliability between health professionals in clinical testing while assessing if a patient has APT (Preece et al, 2008). One health professional will assess you and say you have an APT while another may say otherwise.

APT is also not related to low back pain. Have a look at this systematic review by Chun et al (2017). In fact, patients that have low back pain had more 'neutral' pelvic (or hip) positions.

For those of you who have been told, APT is also not related to hip flexor tightness (Elliot et al, 2017) or a weak core (Walker et al, 1987). Neither does your hamstrings length or flexibility affect APT (Li et al, 1996).

So do not worry if someone or a health professional tells you that you have an anterior or posterior pelvic tilt for that matter. It may be changeable and may help reduce pain and/ or symptoms. It is not something that you need to be overly focused on. Treating the cause of the problem is much better than just treating the symptoms.

References

Boukabache A, Preece SJ, Brookes N et al (2021). Prolonged Sitting And Physical Inactivity Are Associated With Limited Hip Extension: A Cross-sectional Study. Musculosk Sci Pract. 51: 102282. DOI: 10.1016/j.musksp.2020.102282

Preece SJ, Willan P, Nester CJ et al (2008). Variation In Pelvic Morphology May Prevent The Identification Of Anterior Pelvic Tilt. J Manual Manip Therapy. 16(2): 113-117. DOI: 10.1179/106698108790818459. 

14 Day Lag Period Between Sleep Deficit And New Injury

Picture by Jeffrey Bown from his book Goodnight Darth Vader

Well, it's that time of the year again, where school has ended (for Singapore schools) and work in the office starts to wind down. Many of our patients are already traveling before the Christmas holiday.

Many of us, in this last month of the year, will experience less sleep due to travel, parties, family, children and shift work.

Though we would love to catch up with sleep when sleep is disturbed, even with training/ exercising taking a lower priority, it becomes more difficult with all the committments.

I often tell my patients (who are still training seriously) that there is up to 51 percent increased risk of injury especially for endurance athletes who get less than 7 hours of sleep per day in the last 2 weeks (Johnson et al, 2020).

The study recruited runners, triathletes, swimmers, cyclists and rowers. Subjective health complaints (SHCs) like psychological/ lifestyle factors, cardiorespiratory and gastrointestinal problems to investigated to see if they were associated with sleep quality, training load and new injury episodes.

Applying a 7 day and 14 day lag period, a shared frailty model was used to investigate new injury risk associations with total SHCs and sleep quality.

The investigators found that 7 day lag psychological/ lifestyle SHCs were significantly associated with new injury risk. This was in contrast to cardiorespiratory and gastrointesinal SHCs were not significantly associated with new injury risk. 

New injury risk had a significant increased association with a 14 day lag if there was less than 7 hours of sleep per day. There was no significant association with total SHCs, sleep quantity and training load factors.

The authors concluded that athletes need to be aware of the lag period between low sleep quality and its subsequent impact on new injury risk. In order to minimise the risk of new injuries, psychological/ lifestyle SHCs and sleep quantity should be considered.

Be mindful. Bear in mind that this end year period may be a time when we are most susceptible to new injury if we are deprived of sleep.

Reference

Johnston R, Cahalan R, Bonnett L et al (2020). General Health Complaints And Sleep Associated With New Injury Within An Endurance Sporting Population. J Sci Med Sport. 23(3): 252-257. DOI: 10.1016/j.jsams.2019.10.013

Physical Activity And Life Expectancy

Earlier this month, I came across an older article (Janssen et al, 2013) about how leisure time physical activity is associated with increases in longevity. Men are expected to gain up to 2.6 hours of life with each hour of moderate activity and 5.4 hours of life per hour of vigorous activity.

Women are estimated to gain up to 5.6 hours of life per hour of moderate activity and 11.3 hours of life for every hour of vigorous activity!

Just last night I saw another article that was published just 2 weeks ago by Veerman et al (2024). The authors investigated how physical activity (PA) levels were associated with mortality rates. Whether low PA reduces life expectancy and how much life expectancy could be improved by increasing PA levels.

Ready for the results? For individuals in the lowest activity quartile, the greatest gain in lifetime per hour of walking would gain them an extra 6.3 hours with each additional hour of walking.

If all individuals were just as active as the top 25 percent of the population, those above 40 would live an extra 5.3 years.

Picture from Veerman et al (2024)

The  authors concluded that higher PA levels will provide a substantial increase in overall population life expectancy. 

So you know what you need to do if you want to live longer.

References

Janssen I, Carson V, Lee IM et al 92013). Years Of Life Gained Due To Leisure-time Physical Activity In The US. Am J Prev Med. 4491): 23-29. DOI: 10.1016/j.amepre.2012.09.056

Veerman L, Tarp J, Wijaya R  et al (2024). Physical Activity And Life Expectancy: A Life-table Anaylysis. BJSM. DOI: 10.1136/bjsports-2024-108125.

Do You Have More Slow Or Fast Twitch Muscle Fibers?

Picture from Bodyworksprime

I always knew I had some decent fast twitch muscle fibers in me. How do I know you may ask? I could always sprint at the end of a race. That's how I won most of the track races I took part in while competing in school competitions. My strategy was always to sit and wait off the leader's shoulder until the last 80-100 m and outkick whoever was there.

So I was very surprised when a newly published paper (Lievens et al, 2024) suggested that only 50 percent of elite coaches and sports scientists (out of > 400) actually know whether their athletes have slow-twitch or fast-twitch muscle fibers. Yet 90 percent of them believe that knowing the dominant muscle fiber type of an athlete is useful for optimizing training and performance.

Humans on average have a roughly 50-50 mix of slow and fast twitch fibers. There can be a huge variation around this average as some people can be mostly slow-twitch while others can be mostly fast-twitch. I have written in more detail about the 3 different types of muscle fibers we have. 

Here is a quick recap. Type I or slow twitch muscle fibers which are the smallest and produce the least amount of forces, but once trained can go all day long without fatiguing. They also help to hold and stabilize our posture.

Type II or fast twitch muscle fibers which are further divided into Type IIa and Type IIx (also known as IIb). These are larger muscle fibers and produce a greater and quicker force (than type I), but have less mitochondria, myoglobin and capillaries (compared to Type I) and are prone to fatigue quicker.

Type IIa (also known as intermediate muscle fibers) is a mixture of Type I and IIx fibers. They use both aerobic and anaerobic energy systems and fatigue slower than Type IIx. Proper training of Type IIa fibers will increase their ability to utilize aerobic energy, translating to greater endurance.

Type IIx are the largest muscle fibers and produces the most forces but are inefficient and fatigue quickly as it has low oxidative capacity and relies on anaerobic energy.

If you have read this far, you may already know more about muscle fibers than 50 percent of the coaches in the article above.

Studies have shown that those with more fast-twitch muscles have a faster last lap sprint in the 1500 m while those with more slow-twitch fibers generally do better in races when they are more evenly paced.

Another study (Swinnen et al, 2024) showed that those with slow-twitch fibers tend to have better running economy (use less energy at a given pace) since slow-twitch fibers uses less energy than fast-twitch fibers. 

The gold standard to know your fiber type is a muscle biopsy which means taking a small piece of your muscle for analysis. It is a really painful process plus who wants to give away hard earned muscle?

That is probably why the coaches surveyed in the Lievens et al (2024) study said they do not know their athletes' fiber type, especially if they coach middle distance, team sport athletes or recreational athletes who were not active previously. 

Coaches in the Lievens (2024) study relied heavily on how high you can jump (or how long you stay in the air). It is a decent proxy for fast twitch muscle fiber testing. Men with a vertical jump in excess of 50 cm (20 inches) and women 35 cm (14 inches) have predominantly more fast-twitch fibers.

Another study found that fast-twitchers can usually do 5-8 reps at a given load (80 max in the study), while slow-twitchers did 11-15 reps. About a third in the study group did 9-10 reps and they had an even mix of fast and slow twitch fibers. Those with more fast-twitch fibers tend to be stronger but note that they fatigue more quickly too.

This has implications for strength training since the 1-rep max calculations used to find how many reps to do at a lower weight will be different for fast versus slow twitch fiber types. Slow twitchers need to do more reps to get a comparable stimulus.

Perhaps a good estimate is how you fare over long versus short distances. Note that it will be affected by factors like how you have trained. This is definitely worth considering when you are deciding what races to compete in or how many reps to do while lifting. 

What muscle fibers you have is not destiny and does not have to determine your athletic goals. It may tell you the best way to get there.

Reference

Lievens E, Van de Casteele F, De Block F et al (02024). Estimating Muscle Fiber-Type Composition In Elite Athletes: A Survey On Current Practices And Perceived Merit. Int J Sp Physiol Perform. 19(11): 1197-1208. DOI: 10.1123/ijspp.2024-0043

Our Team Building Event

Guess what we did for our team building event? What do you see? Get the answer here.

Cardio Before Or After You Lift Weights?

Picture from Diamondback Fitness

Last week's post was about weekend warriors, who did not have enough time to exercise during weekdays. My patient who read that post was asking me if she should lift weights or do cardio first if she wanted to do both back to back. I told her it depends on her athletic goals and how much time she can spare working out. 

So should you lift weights first or cardio (or aerobic training) first?

I suggested weight training first followed by cardio (or aerobic exercises). Weight training involves external loading with barbells, weights, kettlebells and resistance bands and has a more acute injury risk if already tired. Especially after a longer aerobic session, your muscles are fatigued and lifting weights after that will elevate your injury risk.

One would usually not be able to lift as much or perform that many reps compared to starting with strength training. Especially if you decide to lift heavier weights.You will definitely do a better job if your muscles are fresh.

Note that if you lift weights before your aerobic exercise it will also inhibit your aerobic performance. Research shows that there will be a reduction in speed, power and stamina. 

Actually when I used to race triathlons, I would often do weight training and then cycle and/ or run after (brick training). I'll be fatigued after the weight training which is the state I would be in after swimming and cycling before attempting the run section anyway. So that made sense for me to always run when I'm already tired to simulate race conditions. 

Lifting weights prior to aerobic exercise will not significantly increase your risk of injury compared to tackling heavy weights when you are already tired. Do aerobic training and weight training on different days to optimize both if you have time. If you are thinking of doing both, go with weight training first.

An exception to the rule for this would be the warm up. Warming up with a bit of light cardio (stationary bike or elliptical etc) prior to weight training (or any other workout) will help prime your muscles, increase blood flow, get your mental focus and nervous system ready for action. 

You can work both strength and cardio simultanesously in the same workout when you perform circuit training or HIIT as it is now commonly called. By minimizing your rest time and prioritizing your work efforts, your heart rate remains elevated while working your muscles to simulate hypertrophy. 

You do get the best of both worlds, burning calories and endurance boosting of aerobic conditioning and the muscle building and power from strength training. Just do not do them every day as your body will not have time to recover sufficiently between sessions.

Reference

Conceicao M, Cadore EL, Gonzalez-Izal M et al (2014). Strength Training Prior To Endurance Exercise: Impact On Neuromuscular System, Endurance Performance And Cardiorespiratory Responses. J Hum Kinet. 30(44) : 171-181. DOI: 10.2478/hukin-2014-0123