Time-Efficient Training Approach as a Solution to Sedentary Occupational Health Risks

Today’s workforce has become increasingly sedentary in comparison with past generations (42). Frequently reported obstacles to achieving recommended amounts of physical activity include poor or insufficient guidance on how to exercise, lack of social support and competence/confidence in physical abilities, poor or limited access to facilities in safe areas, fear of injury, and lack of time (18,20,44). The most often reported obstacle to achieving recommended levels of physical activity is lack of time. Populations reporting time constraints as a barrier to physical activity includes college, nursing, and medical students (5,19), working adults (18), emergency medical services employees (37), and healthcare occupations (13). In addition, sedentary occupations are a contributor to physical inactivity. As defined by the United States Department of Labor’s Dictionary of Occupational Titles, “Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time,” (40). Furthermore, sedentary jobs may entail those employees who exert up to 10 lb of force for up to 1/3 of their workday (40). Physical inactivity and sedentary behavior traits are noted as the fourth leading cause of mortality and ranked 11th in terms of disease risk across the lifespan, worldwide (43). In 2010, approximately 3.2 million deaths were attributable to physical inactivity and low levels of physical activity (23). A 2014 study by Clemes et al. concluded that as much as 71% of study participants spent their workday in a sedentary state (8). Moreover, the cumulative sedentary behavior by the study participants on non-workdays has the potential to lead to further health complications. Table 1 provides a summary of commonly diagnosed health consequences as a result of physical inactivity from several studies (3,7,9,24,30,31).

Table 1. Common Health Consequences and Physical Ailments in Sedentary Occupations (3,7,9,24,30,31)

The 2011 American College of Sports Medicine (ACSM) position statement calls for American adults to complete at least 150 min of moderate physical activity per week or a minimum of 75 min of vigorous intensity exercise per week (12). Furthermore, it is recommended that at least 30 min of physical activity be performed 3 – 5 days per week depending on exercise intensity level (12). Additionally, resistance training is recommended at a minimum of 2 – 3 days per week, targeting all major muscle groups (12). Despite the physical activity guidelines that have been set forth for adults, many are not achieving the benchmarks listed. Survey results published in 2018 from nearly 480,000 adult respondents (ages 18+) indicated that approximately 16% completed the recommended amounts of aerobic and resistance exercises, 23.7% completed solely aerobic activity, and 4.5% completed only resistance training (45).

As a solution, the concept of time-efficient training may be a viable option for busy working adults who experience time as a barrier to exercise. Time-efficient training sessions are comprised of bilateral, multi-joint, compound movements, exercise-specific warm-ups with minimal focus on static stretching, and the optimization of intensity, volume, frequency, and volume-load per workout (20). Moreover, improved cardiovascular health and increased calorie expenditure may be attained in a time-efficient manner via the use of high-intensity interval training (HIIT) implemented with several modes of aerobic endurance exercise (25). HIIT is characterized by multiple, repeated high-intensity intervals of >90% VO₂max, focused on utilizing W:R ratios of 1:1 to 1:8 and virtually any mode of aerobic endurance exercise (25,28). Regarding training frequency, the use of several short training sessions is recommended, if possible. Cuthbert et al. supports the idea of shorter training sessions by way of a division of total planned weekly training volume across more frequent workouts throughout the week (10). Ultimately, the use of time-efficient training methods to achieve recommended physical activity levels may be obtained through less frequent traditionally structured training sessions (approximately 45 min) or by way of shorter (approximately 15 – 30 min) more frequent workouts (10,23,32).

Benefits of Time-Efficient Training

Dividing total daily training volume across multiple, more frequent workouts promotes improvements in numerous physiological qualities. Bonder et al. noted improvements in lower-body strength via the use of three 15-minute training sessions per week for four weeks within active law enforcement officers, achieving an average increase of 4.5% weight lifted in the hex-bar deadlift three repetition-maximum (3RM) (6). According to Fyfe et al., the maintenance or improvement of previously acquired levels of muscular strength, through minimal “doses” of resistance training, can be beneficial in promoting improvements in quality of life and independence thus preserving functional capabilities across the lifespan (10). In addition, Cuthbert et al. indicated that populations with prior resistance training experience may improve levels of strength through fluctuations in volume and intensity prescriptions over the course of shorter more frequent workouts (10). A narrative review by Iversen et al. concluded as few as four sets per muscle group per week, with the use of weights ranging in intensity from 6 – 15 RM, may yield improvements in both muscular hypertrophy and strength (20). Thus, a focus on increasing skeletal muscle tissue, within reason, may be beneficial to maintain or improve strength, minimize the atrophy process of type II muscle fibers, blunt the potential loss of strength, and improve body composition, particularly in populations with minimal resistance training experience (10,14,38). Lastly, research by Häkkinen and Kallinen with female athletes noted statistically significant adaptations in neuromuscular functioning (p < 0.01), suggesting the potential to improve muscular power output (16).

Regarding cardiovascular health and muscular endurance, in a study among military personnel, Kilen et al. noted improvements in the “micro-training” group in both areas (22). Their “micro-training” group was comprised of 21 subjects that completed nine 15-minute training sessions per week while the “classical” training group completed three 45-minute training sessions per week. Specifically, the micro-training group experienced a 6.5% increase in peak oxygen uptake (measured in mL•min-1) during an incremental incline treadmill running test set at a fixed speed along with an approximate 9% improvement in number of lunges performed in two minutes in comparison with the "classical" training group. Schleppenbach et al. noted HIIT, specifically speed interval training (SIT), displays the potential to improve individual calorie consumption during the workout for both regular exercisers and sedentary individuals, leading to potential improvements in body composition (32). Regular exercisers were found to expend approximately 30 more calories per SIT session when compared to those individuals utilizing circuit training. Additionally, sedentary individuals had a caloric expenditure of approximately 11 more calories during SIT versus circuit training. Vaara et al. suggest improvements in muscular endurance have an inverse relationship with elements of metabolic syndrome including triglyceride levels, low-density lipoprotein (LPL), cholesterol, blood glucose, and high blood pressure along with a positive association with high-density lipoprotein (HDL) cholesterol (41). Heightened levels of muscular endurance also displayed a negative relationship with cardiovascular risk factors. Table 2 summarizes the physiological benefits that have been reported with the implementation of time-efficient training methods.

Table 2. Summary of Potential Physiological Health Benefits Via Time-Efficient Training (6,10,11,16,20,22,32)

Foundations of Time-Efficient Training

There are three main components that must be adhered to in order to derive the most benefit from time-efficient workouts. Namely, the structure and length of the warm-up, proper exercise selection, and rest period length. Each component is further elaborated on below.

Warm-Up Structure

A warm-up is often performed with the intent of preparing the individual for the upcoming workout and decreasing the likelihood of injury (21). In addition, the length of a warm-up is typically 5 – 15 minutes and progresses from general to specific movement patterns, relative to the upcoming training (1). The use of dynamic specific warm-ups prior to exercise are indicated to promote optimal strength and power output during training, thereby optimizing overall performance (26). In order to utilize available time, the use of a specific warm-up is recommended, prescribing submaximal loads of the upcoming exercise(s), due to minimal evidence supporting the use of a general warm-up (20). When preparing to undertake aerobic endurance exercise, such as with interval training or HIIT workouts, a gradual progression from walking to a full run over the course of 10 – 15 min is recommended (25).

Exercise Selection

While a wide array of exercises are available to choose from when designing a workout routine, those exercises including the greatest amount of musculature and connective tissue while prioritizing multiple joints should be selected. Despite the relative ease associated with learning single-joint movements, multi-joint movements should take precedent as they allow for the greatest amount of musculature to be stimulated during training (20). Furthermore, bilateral exercises (those movements utilizing both sides of the body at the same time) should be prioritized in time-efficient training programs as unilateral exercises (movements utilizing one side of the body at a time) may take more time to perform, leaving little time to complete supplementary exercises (20). Should the goal of the workout be focused on unilateral training, the concept of a “split routine” may be utilized to train different muscles and groups of muscles on different days of the week (35). When implementing interval and HIIT style training, the use of several modes of aerobic endurance exercise may be selected (25).

Rest Period Length

Perhaps the most notable component of a time-efficient training program is the amount of inter- and intra-set rest to observe while exercising. The common theme with each of the methods to be described herein is the manipulation of rest period length. By way of decreasing allotted rest time, pairing exercises of opposing agonist and antagonist muscle groups, different regions of the body, or providing intra-set rest, downtime between movements may be minimized. A systematic review by Grgic et al. proposes that untrained individuals may benefit from rest intervals of less than 60 s in length to improve strength measures, while trainees with prior resistance training experience may necessitate the need for rest intervals lasting two minutes or longer (15). When the focus of training is to improve cardiovascular health, interval and HIIT training may be implemented by following pre-determined work-to-rest ratios (W:R) from 1:1 to 1:8 using intensities of more than 90% VO₂max (25,28). The use of short intervals of 45 s, and long intervals of 2 – 4 min, may also potentially be used dependent on the physiological adaptation being sought and time available to train (28). As an investigation from Hoare et al. indicated that 50% of inactive adults listed "lack of time" as the most common barrier to achieving recommended amounts of weekly exercise, the use of rest intervals not exceeding two minutes is paramount when time is of the essence (18).

Time-Efficient Training Methods

To maximize time available to exercise, the use of several different training methods may be employed. Specifically, the choice of method utilized should be appropriate to match the individual’s desired outcomes (e.g., muscular strength, power, endurance, hypertrophy, cardiovascular benefits). Most notably, strict and minimal rest period times should be utilized.

Potential methods to optimize training time include the use of supersets, compound sets, rest-pause training, resistance circuit, interval training, and HIIT. The use of supersets involves selecting two exercises of opposing muscle groups (agonist-antagonist) and performing them back-to-back, with no rest between sets (20,29). Examples of types of pairings include anterior-posterior movements, upper- and lower-body exercises, and pushing-pulling selections. Findings from Iversen et al. (20) suggest that an 8 – 12 RM loading scheme, with each exercise performed to muscular failure, be employed to maximize time-efficiency when prescribing supersets (21). The use of compound sets involves the same repetition, set, and rest period scheme as supersets, except the two exercises performed back-to-back are to target the same muscle group (35). In terms of efficiency, the primary drawback with using this method is that only one group of muscles or pattern of movement can be trained concurrently, limiting its efficacy in providing a whole-body stimulus for those individuals with minimal time and days to train during their week (20). Thus, the use of compound sets is suggested solely for those individuals able to dedicate themselves to several workouts per week. Utilization of rest-pause training involves performing multiple sets at submaximal intensities (< 80% 1RM), with each set being performed to muscular failure until a pre-determined number of repetitions has been completed (20). Unique to rest-pause training, the use of brief (20 – 30 s) inter-set rest periods follows the end of each set and prior to beginning the next. Prestes et al. (27) demonstrated that use of the rest-pause method in an experimental group (n=9) with a goal of 18 total repetitions per exercise showed similar results to that of a traditional, multiple set training group (n=9) performing 3 sets of 6 repetitions at 80% 1 RM with 2-min rest periods between sets. Both the rest-pause and traditional training groups utilized a variety of upper and lower body exercises focused on muscular strength.

In addition, the experimental group utilizing the rest-pause method experienced greater improvements in muscular hypertrophy and endurance when compared with the traditional, multiple sets training group. As a result, this type of training may be particularly suitable to elicit improvements in muscular hypertrophy, strength, and endurance. Ultimately, due to the high intensity of this training technique, it is recommended for implementation with those individuals having prior resistance training experience (20). In addition, the use of circuit resistance training may be advantageous when the goal is to promote improvements in muscular endurance and body composition by way of reduced body mass and body fat percentage (4,35,36). Moreover, interval training and HIIT may be beneficial to elicit improvements in cardiovascular health, aerobic endurance, individual recovery oxygen consumption levels, and body composition (2,25,32). While the classification of training styles may often be used interchangeably, the difference lies in the amount of rest prescribed with each type of training. Circuit training is performed with minimal to no rest between exercises while interval training and HIIT utilizes predetermined W:R ratios to elicit specific adaptations in the body’s bioenergetic pathways including phosphagen, glycolytic, and oxidative systems (17). Alternatively, HIIT utilizes repeated high-intensity intervals of more than 90% VO₂max, with W:R ratios of 1:1 to 1:8 and virtually any mode of aerobic endurance exercise (25,28). Ultimately, HIIT training sessions may last between 5 – 30 min dependent upon the client’s ability level and current aerobic training foundation (25). Tables 3 – 7 provide sample time-efficient training programs utilizing the various methods discussed to improve muscular strength, hypertrophy, power, endurance, and cardiovascular health.

Table 3. Strength Program via Rest-Pause Method

Table 4. Hypertrophy Program via Supersets

Table 5. Power Program

Table 6. Muscular Endurance Program via Circuit Resistance Training

Table 7. Cardiovascular Health Program via High Intensity Interval Training (HIIT)

Conclusion

Lack of time is often the primary obstacle to inactive, sedentary adults achieving recommended amounts of weekly physical activity. Furthermore, a broad spectrum of occupations and career paths lend themselves to promoting sedentary behavior traits. In turn, physical inactivity may eventually lead to an increased risk and incidence of numerous health consequences and physiological ailments. The foundations and benefits of time-efficient training methods have been presented as a viable option to combat physical inactivity associated with sedentary occupations. In conjunction with the supervision of a certified personal trainer or strength and conditioning coach, the methods discussed herein may be implemented to confer a variety of overall health and physiological improvements while minimizing the time necessary to dedicate to training.

This article originally appeared in Personal Training Quarterly (PTQ)—a quarterly publication for NSCA Members designed specifically for the personal trainer. Discover easy-to-read, research-based articles that take your training knowledge further with Nutrition, Programming, and Personal Business Development columns in each quarterly, electronic issue. Read more articles from PTQ »

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