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The Benefits of Rest Intervals During Resistance Training


The Benefits of Rest Intervals During Resistance Training

Hey everyone, my name’s Taylor Kennon and I’m the newest movement specialist at Perform for Life. I recently graduated with my master’s degree in Kinesiology and I’m excited to begin my career here in San Francisco. Something that really interests me is the physiology behind exercise and the research supporting it. I wanted to write a little bit about rest interval timing because it’s an important variable that, when used properly, can be used to amplify the effects of a good exercise program.

Exercise causes adaptation in the body because it causes physiological stress, which causes the body to improve. Some examples of physiological stress from an acute bout of exercise are glycogen storage in the muscle, acidity in the muscle and blood, and decreased enzyme availability. All of these stresses cause the body to in turn increase its capacity to handle that specific stress in the future, resulting in an increase in performance for future workouts. For example, after the body becomes more acidic following a resistance training bout, the body can handle (buffer) that amount of acidity more efficiently in the future.

There is ample research advocating the use of multiple sets of an exercise during resistance training to induce increases in muscular strength and hypertrophy (muscle growth) adaptations in the body (Kramer et al., 1997). The amount of time taken between these sets are known as rest intervals, which have important implications in both acute responses and chronic adaptations to a resistance training program. According to the National Strength and Conditioning Association (NSCA), rest intervals should differ based off of the training goal, whether it be muscular strength, muscular hypertrophy, or muscular endurance.

If multiple sets of an exercise are used, the physiological stress to the body can be repeated, causing greater adaptation and inducing the associated increases in performance (Krieger, 2009). Each type of goal calls for a different rest interval, and if the rest intervals are correct according to the training goal, the stress can be even greater. That’s why rest intervals are so important: they allow for manipulation of the amount of physiological stress. Take a look at the table below to see a few different ideal rest period lengths:

Source: NSCA, Essentials of Strength and Conditioning (Baechle & Earle, 2000)  

Source: NSCA, Essentials of Strength and Conditioning (Baechle & Earle, 2000)  

Depending on the training goal, long or short rest intervals should be used. For example, if the training goal is muscular hypertrophy or muscular endurance, shorter rest intervals are required. This is because these two training goals require incomplete rest to cause a greater amount of stress to the body. Conversely, strength (and power) require higher rest intervals because this training goal requires a more complete rest to perform in subsequent sets. For example, if you perform the bench press for 5 repetitions at 85% of your 1 repetition maximum (strength training parameters), you would need a long rest interval to perform on the next set due to the high intensity (weight). With muscular hypertrophy and endurance, a shorter rest is more ideal because the intensity isn’t as high and one could still perform optimally in subsequent sets, even with the short rest intervals.

Another important thing to note is the effect that rest interval length has on hormone production. There’s an abundance of research supporting the claim that shorter rest between sets of an exercise causes a greater hormone response for exercise when measuring for anabolic hormones such as testosterone and growth hormone. Indeed, a study by Buresh and Berg (2009) showed that the anabolic hormone response is greater with 1-minute rest intervals when compared to 2.5-minute rest intervals during resistance training. Both of these hormones are paramount to building and maintaining muscle mass.

If repeated sets are used in a resistance training program, rest intervals are important to consider so that the correct amount of muscular recovery can be obtained between sets, depending on the training goal. If rest intervals are used properly, the appropriate amount of physiological stress can be obtained, leading to the associated hormone and performance benefits. At Perform for Life, we want to help you reach your fitness goals, and using correct rest intervals as a part of an effective program designed to properly stress the body will help you optimally do so.



Kramer, J. B., Stone, M. H., O'bryant, H. S., Conley, M. S., Johnson, R. L., Nieman, D. C., ... & Hoke, T. P. (1997). Effects of single vs. multiple sets of weight training: impact of volume, intensity, and variation. Journal of strength and Conditioning Research, 11, 143-147.

Krieger, J. W. (2009). Single versus multiple sets of resistance exercise: a meta-regression. The Journal of Strength & Conditioning Research, 23(6), 1890-1901.

Book source: Baechle, T. R., Earle, R. W., & National Strength & Conditioning Association (U.S.). (2000). Essentials of strength training and conditioning. Champaign, Ill: Human Kinetics.

Buresh, R., Berg, K., & French, J. (2009). The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training. The Journal of Strength & Conditioning Research, 23(1), 62-71.




Screw the Scale

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Screw the Scale

I get this question a lot: “I just started exercising, so why am I gaining weight?” I’m pretty sure many of us have experienced this. We start a new training program and the number on the scale stays the same, or even worse, it goes up. Truth is, this is completely normal - and temporary. When we start a new exercise program and our bodies aren’t adjusted to that type of stress, our muscles may become inflamed. Most of the weight you see on the scale is probably not fat, but temporary water weight due to inflammation. However, it could also be an increase in muscle mass. Yay!

Again, one reason you may have gained weight in your first month of training is due to inflammation. When you work out a given muscle, you’re basically causing tears in your muscle fibers. This is usually referred as "microtrauma" and is why you feel sore the next day. But on the bright side, your body heals these little tears and makes your muscles stronger as you continue to lift heavy weights - essentially, your body adapts to the stress. That’s how you can get stronger and more fit: you create adaptation to whatever you’re doing, whether its cardiovascular training or strength training. During the first month of a new training program - especially if you’re new to fitness - there’s definitely going to be a lot of adaptation going on and these fluid build-ups caused by inflammation might show up on the scale. But don’t worry, once your body is adapted to this stress, the scale should go back down. Just keep working hard and trust the process.

Another reason why you might see weight gain within the first few weeks of training is that you’re building muscle faster than you’re losing fat. Muscle is more dense than fat, thus taking up less space. Next time, rather than stepping on a scale, measure your circumference instead. It’s often the case that, if you do gain muscle mass, the scale might go up, but you’ll probably fit better in your jeans.

Often times, we define fitness by body weight. I’ve seen so many people throughout their fitness journeys lose motivation because the scale wasn’t budging. But what does that number really mean? Does that mean they’re not progressing? Not getting stronger? Not becoming healthier? Chances are, the answer is no. Place the scale aside and focus on what really matters. Do your clothes fit better? Do you feel better? Are you happier? If the answer is yes, disregard the scale.

People may not consider the early changes to their bodies as a good thing. The key is to not let that number define your hard work and discourage you from working out or eating healthy. So, instead of weighing yourself, pay attention to what really matters: strength, endurance, health, how you feel, and most importantly, happiness. You’re so much more than just a number! Again, once you’ve been working out consistently, your muscle gains and water weight should stabilize. So keep doing what you’re doing and don’t lose faith. Be patient. Stick with your program. Don’t let any arbitrary number tell you how well or not you’re doing if you’re seeing positive physical changes. Like what successful people say, “Age is just a number.” Well..your weight is just a number, too.







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How to Become a Posture Pro


How to Become a Posture Pro

Are you aware of your posture?

It’s not all about puffing your chest out or rolling your shoulders back, as a matter of fact that should be the least of your worries. Yes, those two factors may help your posture, but for how long or how long until you feel uncomfortable? We all want less back pain, less stress, less neck and shoulder pain, improved breathing, and improved energy. Let yourself control the outcome. Body awareness is one aspect that is overlooked but can be the most useful when trying to correct your posture.

“Posture isn't just physical.  It's a psychophysical (mind/body) state that we get into in response to our environment, emotions, and people with whom we interact.”

We habitually tend to put ourselves in postural problems by overly tensing certain muscles in the neck and shoulders that actually pull our heads out of alignment with the spine. Being aware of how your body feels and concentrating on your body movements one thing leads to another; it will allow you to have better focus in general, your body will be in a better alignment,  and can help reduce pain and stress. With the proper help at P4L, learning these aspects will help decrease your pain and discomfort.

Key training tools you’ll gain from us?

  • Observations : we observe and assess your movements
  • Breathing : different ways of breathing that create proper balance in core stability and muscle distribution
  • Corrective exercises and proper queues : modified exercise to fit your body type
  • Proper coaching on body awareness (what/how you should feel)
  • Results and feedback  : measurements of spinal and pelvic angles to show improvements in alignment

Practice, practice, practice! How else will you become good at something? Practicing proper posture alignment with the help of body awareness takes time, concentration, and persistence. For example, reflect on that time when you took the LSATS, or when you had your first corporate presentation (now, you’re a pro), or something even as simple as riding a bike. It does not happen all at once, but being mindful about your body can create an improvement in exercise performance, decreased stress and pain, and better concentration.




Learn more about Coach Brandon here





Steph Curry and Why We Should Focus on A Whole Body Approach to Fitness


Most of you probably know who Steph Curry is, but for those who don’t, Wardell Stephen “Steph” Curry II plays for the Golden State Warriors.  He is known for his agility on the court and is the undisputed king of three-point shots.

But just a few years ago, Steph was spending more time on the bench than on the court.  Ankle injuries in the 2011-2012 season allowed him only to play 26 of 82 games. Curry’s future in the NBA was in question, but then he experienced a miraculous turn around: the next season he played 78 games of 82 games, and the following season he managed another 78 games.  This past season Steph led the Golden State Warriors to their first NBA Championship since 1975, playing 80 out of 82 games and earning himself title of 2015 NBA MVP!  Steph continues his streak into the current season and he looks to be leading the Warriors to their second consecutive NBA Championship.

How did such an amazing turn around happen?  There was no single silver bullet that turned around Steph’s career: it took a multi-disciplinary full body approach. There was some major damage to the ankles that required some surgical intervention and he did have to go under the surgeon’s knife.  He also started wearing a specialized ankle brace.  These were no doubt essential to his recovery, but the most important piece of the puzzle came when the Golden State Warriors hired Keke Lyles as the new Director of Performance. Lyles did a FULL BODY ANALYSIS of Curry and realized that his ankle problem was not really an ankle problem at all: it was a hip problem!  Full body movement analysis revealed that his hip was not providing his ankle the support and stability it needed.  In short, his ankle was trying to do the work of his hip.  Curry then engaged in a rehabilitative program that allowed better hip integration into his movement.  His amazing success is a testament to the efficacy of the full body approach.

We can learn a couple things from this super star’s example. 

1) First, you need to have a good health team

There was no one intervention that saved Curry’s career.  It was a combination of surgery, orthotics, refined exercise protocols, and hard work.

2) Second, the site of the pain and the source of the pain were not one in the same. 

Whether you seek performance or wellness, the body demands a holistic approach.  When we deal with problems in isolation, we often miss issues of interdependence – a weakness in one area of the body can manifest itself as pain or dysfunction in another part of the body.

Full movement screens are thankfully now becoming more and more common, but it is not yet a universally adopted practice in the fitness industry.  Here at Perform For Life, we use a customized full body approach that combines several movement screens including the Functional Movement Screen, Selective Functional Movement Analysis, and the NASM Corrective Exercise Specialist.  Additionally, all of our trainers utilize the static postural assessments developed by the CHEK Institute.  These tools allow our movement specialists to get a global view of the body, and better design and prioritize your movement prescription.  To schedule a full body movement screening and get started click HERE