June 12, 2018

Polarized vs. Threshold Training Intensity Distribution

Rosenblat MA, Perrotta AS, and Vicenzino B. Polarized vs. threshold training intensity distribution on endurance sport performance: A systematic review and meta-analysis of randomized controlled trials. J Strength Cond Res XX(X): 000-000, 2018

The objective of this review was to systematically search the literature to identify and analyze data from randomized controlled trials that compare the effects of a polarized training model (POL) vs. a threshold training model (THR) on measurements of sport performance in endurance athletes. This systematic review and meta-analysis is registered with PROSPERO (CRD42016050942). The literature search was performed on November 6, 2016 and included SPORTDiscus (1800-present), CINAHL Complete (1981-present), and Medline with Full Text (1946-present). Studies were selected if they included: random allocation, endurance-trained athletes with greater than 2 years of training experience and V[Combining Dot Above]O2max/peak >50 ml·kg·min, a POL group, a THR group, assessed either internal (e.g., V[Combining Dot Above]O2max) or external (e.g., time trial) measurements of endurance sport performance. The databases SPORTDiscus, Medline and CINAHL yielded a combined 329 results. Four studies met the inclusion criteria for the qualitative analysis, and 3 for the meta-analysis. Two of the 4 studies included in the review scored a 4/10 on the PEDro Scale and 2 scored a 5/10. With respect to outcome measurements, 3 studies included time-trial performance, 3 included V[Combining Dot Above]O2max or V[Combining Dot Above]O2peak, 2 studies measured time-to-exhaustion, and one study included exercise economy. There was sufficient data to conduct a meta-analysis on time-trial performance. The pooled results demonstrate a moderate effect (ES = -0.66; 95% CI: -1.17 to -0.15) favoring the POL group over the THR group. These results suggest that POL may lead to a greater improvement in endurance sport performance than THR.

Link: https://www.ncbi.nlm.nih.gov/pubmed/29863593

December 17, 2017

Running-Related Injury Risk Screening

There are many factors related to running injuries. Other programs typically address one or two components, however, we believe that it is important to address all aspects of running.


Initial Assessment
  • Review past and current medical history
  • Running experience and previous running-related injuries
  • Running and fitness related goals
  • Orthopaedic assessment to address risk factors for running-related injuries
  • Running gait assessment that addresses biomechanical risk factors for running-related injuries

Orthopaedic Assessment Follow-Up
  • Review orthopaedic findings
  • Corrective exercises to address issues

Running Gait Assessment Follow-Up
  • Review findings
  • Biomechanical corrections

Training Program Educational Session
  • Training load variables
  • Monitoring training load
  • Structuring a training program
  • Continuous training versus interval training
  • Progressing a training program

January 6, 2017

Patellofemoral pain syndrome (PFPS)

Patellofemoral pain syndrome is a term to describe a group of pathologies associated with anterior knee pain. 

Decreased quadriceps range of motion (ROM) (3)
Decreased gastrocnemius ROM (3)
Dynamic valgus collapse (2)
Decrease quadriceps strength (1)
Decrease hamstring strength (1)

1. Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. A prospective investigation of biomechanical risk factors for patellofemoral pain syndrome: The joint undertaking to monitor and prevent ACL injury (JUMP-ACL) cohort. Am J Sports Med 2009;37(11):2108-2116.

2. Holden S, Boreham C, Doherty C, Delahunt E. Two-dimensional knee valgus displacement as a predictor of patellofemoral pain in adolescent females. Scand J Med Sci 2015;Epub ahead of print.

3. Witvrouw E, Lysens R, Bellemans J, Cambier D, Vanderstraeten G. Intrinsic risk factors for the development of anterior knee pain in an athletic population. A two year prospective study. Am J Sports Med 2000;28(4):480-489.

Search Date
November 14, 2016

Search String
(patellofemoral syndrome OR patellofemoral pain OR pfps) AND (risk factor*)

Search Results
CINAHL Complete = 93
Medline with Full-text = 110
SPORTDiscus = 66

Study Methodology


Internal validity
Internal validity reflects the quality of the study design, implementation and data analysis in order to minimize the level of bias and determine a true 'cause and effect'

External validity
External validity describes the circumstances under which the results of the research can be generalized


Sample size
This is the number of subjects included in the study from a given population. Larger sample sizes tend to be more representative of the population

Participants are randomly assigned to one of two or more interventions. Randomization minimizes the risk of confounding variables, reduces the risk of bias, and allows for examination of direct relationships. A major limitation of using an RCT is that it is impossible to obtain a true random sample of the population (2). This can make it difficult to generalize the results.

Concealed allocation
The person responsible for determining whether a subject was eligible for inclusion in the trial should be unaware of the group the subject is allocated (6). If allocation is not concealed, the decision about whether or not to include a person in a trial could be influenced by knowledge of whether the subject was to receive treatment or not. This could produce systematic biases in an otherwise random allocation (6).

This is a method to prevent study participants, as well as those collecting and analyzing data from knowing who is in the intervention group and who is in the control group (1). When subjects are blinded, it is less likely that the results of the treatment are due to a placebo effect (6). Blinding assessors prevents their personal bias from affecting the results (6).

Baseline comparability
Baseline comparability involves a comparison of the baseline values of the groups (intervention and control). There should be statistically significant difference between groups. An appropriate randomization should ensure that groups are similar at baseline. This may provide an indication of potential bias arising by chance with random allocation (6). A significant difference between groups may indicate an issue with randomization procedures (6). 

The intervention should be described in enough detail for reproducibility. An inadequate description decreases internal validity as it is unclear of the exact mechanism that led to the change in outcomes.

Adequate follow-up
The number of subjects who completed the trial to provide follow-up data for statistical analysis must be sufficient. The PEDro group states that data collected from a minimum of 85% of subjects increases internal validity (6). It is important that measurements of outcomes are made on all subjects who are randomized to groups. Subjects who are not followed up may differ systematically from those who are, and this potentially introduces bias. The magnitude of the potential bias increases with the proportion of subjects not followed up (6).

Intention-to-treat analysis
This is a strategy that ensures that all subjects allocated to either the treatment or control groups are analyzed together as representing that treatment arm, whether or not they received the prescribed treatment or completed the study (1). When patients are excluded from the analysis, the main rationale for randomization is defeated, leading to potential bias (6).

Between-group comparisons
This comparison is a statistical comparison of one group with another. It is performed to determine if the difference between groups is greater than can plausibly be attributed to chance (6).

Point estimates (effect size) and variability
A point estimate or effect size is a value that represents the most likely estimate of the true population (4). Some examples include the mean difference, regression coefficient, Cohen's d, correlation coefficient.

It is important to consider the variability of the effect size (point estimate). A few examples of variability include: the standard deviation, standard error of the mean, and a range of value. The standard deviation is an estimate of the degree of scatter (variability) of individual sample data points about the mean of a sample (3).

Study limitations
A description of the limitations of the study design and methodology allows for transparency as it should describe potential biases. This includes an explanation of possible errors in the internal and external validity.


1. Akobeng A. Understanding randomized controlled trials. Arch Dis Child 2005;90:840-844.

2. Carter R, Lubinsky J, Domholdt E. Rehabiliation Research. 4th ed. 2010. Elsvier; St. Louis, Missouri.

3. Gaddis G, Gaddis M. Introduction to biostatistics: part 3, sensitivity, specificity, predictive value, and hypothesis testing. Ann Emerg Med 1990;19:145-151.

4. Nakagawa S, Cuthill I. Effect size, confidence interval and statistical significance: a practical guide for biologists. Biol Rev 2007;82(4):591-605.

5. Pannucci C, Wilkins E. Identifying and avoiding bias in research. Plast Reconstr Surg 2010;126(2):619-625.

6. Physiotherapy Evidence Database. PEDro Scale (1999). http://www.pedro.org.au/english/downloads/pedro-scale/. Accessed on January 27, 2015.

February 22, 2015

The effects of aerobic high-intensity interval training on endurance performance. A systematic review of randomized controlled trials.

Michael Rosenblat


High-intensity interval training (HIIT) involves performing a set of multiple bouts of exercise that are completed above the anaerobic threshold (LT2). HIIT programs can be differentiated by the dominant system used to produce energy during the interval session. Anaerobic high-intensity interval training (AnHIIT) involves exercise bouts that are less than two minutes in duration, whereas aerobic high-intensity interval training (AeHIIT) involves exercise bouts that are greater than two minutes. The purpose of this review is to systematically evaluate the available evidence on the effects of different AeHIIT training programs on markers of endurance performance in trained and highly-trained endurance athletes.
There is high level evidence demonstrating that AeHIIT can improve VO2peak in state/provincial-level male and female rowers.
There is moderate level evidence that demonstrates that AeHIIT can improve stroke volume in endurance-trained male athletes.
There is moderate level evidence that demonstrates that AeHIIT can improve LT2 (as a percent of VO2peak) in well-trained, competitive endurance athletes (middle distance runners, triathletes and 10 km runners).
There is both high and moderate level evidence that shows that AeHIIT can improve TT performance in well-trained, state/provincial-level male and female rowers, and endurance-trained male athletes, respectively.
There is moderate level evidence that demonstrates that AeHIIT can improve exercise efficiency in trained male and female cyclists, and endurance-trained male athletes.
There is moderate level evidence that indicates that AeHIIT improves TTE in trained male and female cyclists, and endurance-trained male athletes.
More high quality research is necessary to accurately assess the effects of AeHIIT on endurance performance. Specifically, this can be accomplished by designing studies that include blinded subjects and assessors, between-group comparisons, and intention-to-treat analysis. Finally, studies that include two or more exercise programs should use a method to calculate the training load.

January 25, 2015

Take two eye of newt and call me in the morning: Why systematic reviews of randomized controlled trials matter?

Michael Rosenblat

How can we determine if an article about some particular area of research accurately assesses the validity of the research on which any conclusions are based? For instance, how can we trust that wearing compressions socks improves running performance when we read an article in a magazine that makes this claim?

February 23, 2013

An evidence-based triathlon training protocol: a case study and narrative review

Michael Rosenblat


·      LT1 (lactate threshold 1) = VT1 (ventilatory threshold 1) = AeT (aerobic threshold)
·      LT2 (lactate threshold 2) = VT2 (ventilatory threshold 2) = AnT (anaerobic threshold) = MLSS (maximal lactate steady state)
·      VO2max = maximal oxygen consumption
·      LIT = low intensity training
·      MIT = moderate intensity training
·      HIT = high intensity training


The goal of any high-performance training program is to increase an athlete’s performance by producing physiological, neurological and metabolic changes that promote success in their particular sport. With respect to physiological adaptations, training can induce both central (cardiac) and peripheral (skeletal muscle) changes. Central adaptations (changes that affect the left ventricle) increase stroke volume and ultimately cardiac output. These changes are most important when considering oxygen consumption, as the limiting factor for increasing VO2max is the body’s ability to supply oxygen to exercising muscles (1). Peripheral adaptations (changes to the structure of skeletal muscle itself) improve VO2max by increasing the body’s ability to uptake and utilize oxygen at the cellular level.
            Recently, it has become clear that performance is not directly related to VO2max, but rather the ability to compete as close to VO2max as possible. In endurance sports, the highest workload at which an athlete can race is considered to be their MLSS (2). MLSS is the highest blood lactate concentration that can be maintained without a progressive accumulation of lactate in the body (2). Therefore, it is important for an endurance coach to not only increase an athlete’s VO2max but also to increase their MLSS to a point as close to their VO2max as possible.
            Currently, there are a number of studies that describe the effects of different programs of various training intensity distributions on endurance athletes, but none of these studies are specifically directed at triathlon. Also, most studies on aerobic training include training periods of 4-weeks up to 6-months. The case study presented here provides the results of an evidence-based, triathlon training protocol from two consecutive training cycles (Training Cycle 1 – 2012 pre-season and the beginning of Training Cycle 2 – 2013 pre-season, approximately 12-months). The reasoning behind including the two training cycles is to show the effectiveness of this training protocol from one season to the next. This will establish the validity of the protocol by demonstrating continued improvement in athletic performance. This is meaningful because it is more challenging to increase the fitness level of a highly trained athlete than of an untrained or moderately trained individual.

December 20, 2012

The effects of stretching prior to exercise on running performance. A systematic review of randomized controlled trials

Michael Rosenblat


Stretching is a type of exercise that places a muscle in a lengthened position. There are two types of stretches that are commonly discussed in the literature including static stretching, a lengthening of a muscle for a long duration, and dynamic stretching, a repetitive controlled movement at the end range of motion. The purpose of this review is to systematically evaluate the available evidence on the effects evidence of stretching on markers of running performance in trained and highly-trained runners.
There is moderate quality evidence that demonstrates a decline in running performance following a static stretching program in trained, long-distance male runners. A second study of similar design, showed no difference in running performance in trained female runner.
There is moderate quality evidence from two that demonstrates a decrease in running economy shown by a change in caloric expenditure during running following a DS program in trained middle- and long-distance male runners.
There is moderate level evidence from three that suggests that stretching prior to running has no effect on perceived exertion during a 30-minute run in trained middle- and long-distance male and female runners.
Studies of greater methodological design are required to provide more conclusive results on the effects of stretching on running performance.

December 14, 2012

Sackett's Levels of Evidence

1a: Systematic Reviews of Randomized Controlled Trials
A review of the literature that incorporates systematic methods to select studies in order to limit selection bias and provide reliable conclusions on a given topic. Only randomized controlled trials are included as part of the selection process.

1b: Randomized Controlled Trials
An experimental study design Subjects are randomly allocated to different groups. The groups are then compared in terms of the outcomes of interest. This design is chosen when testing the effectiveness of a treatment, or to compare several different forms of treatment.

2: Cohort Studies
An epidemiological research design that works forward from cause to effect, identifying groups of participants thought to have differing risks for developing a condition or characteristic and observing them over time to determine which group of participants are more likely to develop the condition or characteristic.

3: Case Control
An epidemiological research design in which groups of individuals with and without a certain condition or characteristic (the “effect”) are compared to determine whether they have been differentially exposed to presumed causes of the condition or characteristic

4: Case-Series
Systematic documentation of a well-defined unit; usually a description of an episode of care for an individual, but sometimes an administrative, educational, or other unit

5: Expert Opinion / Narrative Review
Narrative reviews tend to be mainly descriptive, do not involve a systematic search of the literature, and thereby often focus on a subset of studies in an area chosen based on availability or author selection. Thus narrative reviews while informative, can often include an element of selection bias.

December 4, 2012

The effects of lower extremity compression garments on performance and recovery in endurance sports. A systematic review of randomized controlled trials

Michael Rosenblat


Lower extremity compression garments are stockings that provide pressure to an individual’s calf or thigh in order to help with circulation. They are most commonly used in hospitals to help prevent circulatory complications that can result from a number of different cardiovascular and metabolic conditions. More recently compression garments have been used in the athletic population as a means to improve sport performance and to decrease recovery time.
The purpose of this review is to systematically evaluate the available evidence of lower extremity compression garments and aerobic exercise on markers of performance, recovery and perception in trained and highly-trained endurance athletes. This review discusses the findings of seven randomized controlled trials, which includes a total of ninety-nine subjects.
There is low-level evidence from one study that demonstrates that wearing compression garments can improve 40km cycling time trial performance in trained male, multisport athletes.
There is moderate-level evidence from one study that demonstrates that wearing compression garments during exercise can increase calf muscle oxygen saturation during a 30-minute run in moderately-trained male athletes.
There is low-level evidence from one study that demonstrates that wearing compression garments can decrease plasma lactate levels immediately following maximal exercise in male subjects who regularly perform endurance exercise.
There is low-level evidence from one study that demonstrates that wearing compression garments can increase running time-to-exhaustion in moderately-trained male runners.
There is low-level evidence from one study that demonstrates that wearing compression garments can decrease perceived muscle soreness 24 hours following a 10km run in trained male runners.
It is important to note that none of the studies found a difference in perceived exertion during exercise when wearing a compression garment versus without a garment. This is significant because some athletes may believe that the garments improve exercise tolerance, however, this is not the case.
More research of higher quality is required to provide further information about the use of lower extremity compression garments during sport and recovery.