Jørgen Ingebrigtsen

Validity of the Acti4 software using ActiGraph GT3X+accelerometer for recording of arm and upper body inclination in simulated work tasks

The validity of inclinometer measurements by ActiGraph GT3X+ (AG) accelerometer, when analysed with the Acti4 customised software, was examined by comparison of inclinometer measurements with a reference system (TrakStar) in a protocol with standardised arm movements and simulated working tasks. The sensors were placed at the upper arm (distal to the deltoid insertion) and at the spine (level of T1-T2) on eight participants. Root mean square errors (RMSEs) values of inclination between the two systems were low for the slow- and medium-speed standardised arm movements and in simulated working tasks. Fast arm movements caused the inclination estimated by the AG to deviate from the reference measurements (RMSE values up to ∼10°). Furthermore, it was found that AG positioned at the upper arm provided inclination data without bias compared to the reference system. These findings indicate that the AG provides valid estimates of arm and upper body inclination in working participants. Practitioner Summary: Being inexpensive, small, water-resistant and without wires, ActiGraph GT3X+ seems to be a valid mean for direct long-term field measurements of arm and trunk inclinations when analysed by the Acti4 customised software.

Yo-Yo IR2 testing of elite and sub-elite soccer players: Performance, heart rate response and correlations to other interval tests

Abstract We examined performance, heart rate response and construct validity of the Yo-Yo IR2 test by testing 111 elite and 92 sub-elite soccer players from Norway and Denmark. VO2max, Yo-Yo IR1 and repeated sprint tests (RSA) (n = 51) and match-analyses (n = 39) were also performed. Yo-Yo IR2 and Yo-Yo IR1 performance was 41 and 25% better (P < 0.01) for elite than sub-elite players, respectively, and heart rate after 2 and 4 min of the Yo-Yo IR2 test was 20 and 15 bpm (9 and 6% HRmax), respectively, lower (P < 0.01) for elite players. RSA performance and VO2max was not different between competitive levels (P > 0.05). For top-teams, Yo-Yo IR2 performance (28%) and sprinting distance (25%) during match were greater (P < 0.05) than for bottom-teams. For elite and sub-elite players, Yo-Yo IR2 performance was correlated (P < 0.05) with Yo-Yo IR1 performance (r = 0.74 and 0.76) and mean RSA time (r = −0.74 and −0.34). We conclude that the Yo-Yo IR2 test has a high discriminant and concurrent validity, as it discriminates between players of different within- and between-league competitive levels and is correlated to other frequently used intermittent elite soccer tests.

Validity of the Acti4 method for detection of physical activity types in free-living settings: comparison with video analysis

This study examined the ability of the Acti4 software for identifying physical activity types from accelerometers during free-living with different levels of movement complexity compared with video observations. Nineteen aircraft cabin cleaners with ActiGraph GT3X+ accelerometer at the thigh and hip performed one semi-standardised and two non-standardised sessions (outside and inside aircraft) with different levels of movement complexity during working hours. The sensitivity for identifying different activity types was 75.4–99.4% for the semi-standardised session, 54.6–98.5% outside the aircraft and 49.9–90.2% inside the aircraft. The specificity was above 90% for all activities, except ‘moving’ inside the aircraft. These findings indicate that Acti4 provides good estimates of time spent in different activity types during semi-standardised conditions, and for sitting, standing and walking during non-standardised conditions with normal level of movement complexity. The Acti4 software may be a useful tool for researchers and practitioners in the field of ergonomics, occupational and public health. Practitioner Summary: Being inexpensive, small, water-resistant and without wires, the ActiGraph GT3X+ by applying the Acti4 software may be a useful tool for long-term field measurements of physical activity types for researchers and practitioners in the field of ergonomics, occupational and public health.

Acceleration and sprint profiles of a professional elite football team in match play

Abstract The aim of this study was to characterise the acceleration and sprint profiles of elite football match play in one Norwegian elite football team (Rosenborg FC). Fifteen professional players in five playing positions took part in the study (n = 101 observations). Player movement was recorded during every domestic home game of one full season (n = 15) by an automatic tracking system based on microwave technology. Each player performed 91 ± 21 accelerations per match, with a lower number in the second compared with the first half (47 ± 12 vs. 44 ± 12). Players in lateral positions accelerated more often compared to players in central positions (98.3 ± 20.5 vs. 85.3 ± 19.5, p < 0.05). Average sprint distance was 213 ± 111 m distributed between 16.6 ± 7.9 sprints, with no differences between first (106 ± 60 m, 8.2 ± 4.2 sprints) and second halves (107 ± 72 m, 8.3 ± 4.8 sprints). Players in lateral positions sprinted longer distances (287 ± 211 m vs. 160 ± 76 m, p < 0.05) and tended to sprint more often (21.6 ± 7.8 vs. 13.0 ± 5.7, p = 0.064) compared to players in central positions. We found more walking and less of the more intense activities during the last third of the season compared to the first. The main finding in this study was that Norwegian elite players had substantially less number of accelerations and fewer but longer sprints than previous studies reported for higher-ranked leagues. Also, less high-intensity activity was found towards the end of the season. Ultimately, these data provide useful information for the fitness coach (1) in planning of position-specific football training and (2) to avoid the decline in high-intensity activities the last third of the competitive season.

Relationships Between Field Performance Tests in High-Level Soccer Players

Abstract Ingebrigtsen, J, Brochmann, M, Castagna, C, Bradley, PS, Ade, J, Krustrup, P, and Holtermann, A. Relationships between field performance tests in high-level soccer layers. J Strength Cond Res 28(4): 942–949, 2014—To reduce athlete testing time, the aim of this study was to investigate the relationship between the Yo-Yo intermittent recovery test levels 1 (IR1) and 2 (IR2) performances, maximal sprinting speed (10, 20, and 35 m), repeated sprint ability (RSA; 7 × 35 m), and submaximal heart rates (HRs) after 2 and 4 minutes of the Yo-Yo IR tests by testing 57 high-level soccer players. All players played regularly in one of 3 highest levels of Norwegian soccer and were tested during 3 sessions on 3 consecutive days. Large correlations were observed between Yo-Yo IR1 and IR2 test performances (r = 0.753, p ⩽ 0.05). Small and moderate correlations were found between 20- and 35-m sprinting speed and Yo-Yo IR1 performance (r = −0.289 and −0.321, respectively, p ⩽ 0.05), whereas 35-m sprinting speed correlated moderately to Yo-Yo IR2 performance (r = −0.371, p ⩽ 0.05). Repeated sprint ability at 10, 20, and 35 m all showed moderate to large correlations to Yo-Yo IR1 performance (r = −0.337 to −0.573, p ⩽ 0.05). Repeated sprint ability at 20 m (r = −0.348, p ⩽ 0.05) and 35 m (r = −0.552, p ⩽ 0.01) correlated moderately and largely to Yo-Yo IR2 performance. In addition, moderate and large correlations were found between submaximal Yo-Yo IR1 HRs after 2 (r = −0.483, p ⩽ 0.01) and 4 minutes (r = −0.655, p ⩽ 0.01) and Yo-Yo IR1 performance, and 2 minutes Yo-Yo IR2 HR and Yo-Yo IR2 performance (r = −0.530, p ⩽ 0.01). Intraclass correlation measures of submaximal HR after 2 and 4 minutes of Yo-Yo IR1 test and after 2 minutes of the Yo-Yo IR2 were 0.92 (coefficient of variation [CV] = 4.1%, n = 33), 0.93 (CV = 3.8%, n = 33), and 0.72 (CV = 2.9%, n = 10). Adjusted ordinary least square (OLS) regressions revealed associations (p ⩽ 0.05) between sprint speed at 20 and 35 m and Yo-Yo IR1 test performance, but only between 35 m and IR2 test performance (p ⩽ 0.05). Further, OLS showed that RSA at 35 m was related to both levels of the Yo-Yo IR test (p ⩽ 0.01), and that submaximal HRs after 2 and 4 minutes were independently associated with Yo-Yo IR1 and IR2 performances (p ⩽ 0.01). In conclusion, Yo-Yo IR1 and 2 test performances, as well as sprint and RSA performances, correlated very largely, and it may therefore be considered using only one of the Yo-Yo tests and a RSA test, in a general soccer-specific field test protocol. The submaximal HR measures during Yo-Yo tests are reproducible and may be used for frequent, time-efficient, and nonexhaustive testing of intermittent exercise capacity of high-level soccer players.

Physical Characteristics and Abilities of Junior Elite Male and Female Handball Players

Abstract Ingebrigtsen, J, Jeffreys, I, and Rodahl, S. Physical characteristics and abilities of junior elite male and female handball players. J Strength Cond Res 27(2): 302–309, 2013—This study first aimed to examine strength, speed, and jumping abilities in 29 male and 29 female junior elite handball players and second to compare Under-18 and Under-16 players in the selected parameters. The players were chosen by the Norwegian Handball Federation, and all were tested in strength (squat and bench press), speed (10-, 30-, and 6 × 30-m repeated sprint ability), and jumping abilities (countermovement jump and squat jump [SJ]). Anthropometric qualities were also measured. Independent t-tests were applied to reveal possible mean differences between the U-18 and U-16 players within each sex. No significant differences in anthropometry were observed between the U18 and U16 players within either sex. Furthermore, we did not observe any significant between group differences among the male players in any of the tested performance parameters. On average, however, the U16 male (n = 14) players performed better in all the tests compared with in the U18 (n = 15) male players. Similarly, we did not find any significant differences in test performances between U18 female players and U16 female players. Still, a few trends (p ⩽ 0.1) were observed because female U18 (n = 14) players were found to sprint faster on both 10 and 30 m and to jump higher in SJ vs. female U16 (n = 15) players. The empirical findings do not confirm the hypothesis of pubertal development and muscle growth leading to taller and heavier U18 players. Furthermore, we expected U18 players to perform better in all the tests when compared with U16 players. Again, the data did not substantiate this, although female U18 players tended to perform better in sprint and SJ compared with the U16 players.

Performance effects of 6 weeks of aerobic production training in junior elite soccer players.

Abstract Ingebrigtsen, J, Shalfawi, SAI, Tønnessen, E, Krustrup, P, and Holtermann, A. Performance effects of 6 weeks of aerobic production training in junior elite soccer players. J Strength Cond Res 27(7): 1861–1867, 2013—This study investigates the performance effects of a 6-week biweekly anaerobic speed endurance production training among junior elite soccer players. Sixteen junior (age 16.9 ± 0.6 years) elite soccer players were tested in the Yo-Yo Intermittent Recovery test level 2 (IR2), 10-m and 35-m sprints, 7 × 35-m repeated-sprint ability (RSA) tests, countermovement jump and squat jump tests, and randomly assigned to either a control group (CG) performing their normal training schedule, which included 4 weekly soccer training sessions of approximately 90 minutes, or a training group performing anaerobic speed endurance production training twice weekly for 6 weeks in addition to their normal weekly schedule. We found that the intervention group significantly improved (p < 0.05) their performance in the Yo-Yo IR2 (63 ± 74 m) and 10-m sprint time (−0.06 ± 0.06 seconds). No significant performance changes were found in the CG. Between-group pretest to posttest differences were found for 10-m sprint times (p < 0.05). No significant changes were observed in the 35-m sprint times, RSA, or jump performances. These results indicate that short-term anaerobic production training is effective in improving acceleration and intermittent exercise performance among well-trained junior elite players.

Physical and Physiological Characteristics of Elite Male Handball Players from Teams with a Different Ranking

Abstract The aim of this study was to examine possible discriminant physical and physiological characteristics between elite male handball players from elite teams with different league rankings. Players from three teams (A, B and C), which competed in the first league of the Greek championship during the season 2011-2012 participated in the study. Team A finished first, B came second and C came eighth out of eleven clubs. Teams A and B also participated in European Cups, and team A won the European Challenge Cup. The players (n=44) were examined for anthropometric characteristics and performed a series of physical fitness tests. Players from teams A and B were taller (6.2 cm (0.7;11.7), mean difference (95% CI) and 9.2 cm (4.0;14.5), respectively), and had a higher amount of fat free mass (6.4 kg (1.1;11.8) and 5.4 kg (0.2;10.5)) compared to those of team C. Players from team A performed better than players from team C in the squat jump (5.5 cm (1.0;10.0)), the countermovement jump without (5.5 cm (0.4;10.6)) and with armswing (6.0 cm (0.7;11.3)) and in the 30 s Bosco test (5.7 W.kg-1 (1.2;10.2)). Also, players from team A outperformed team B in mean power during the Wingate anaerobic test (WAnT, 0.5 W.kg-1(0;0.9)) and in the Bosco test (7.8 W.kg-1 (3.4;12.2)). Overall, players from the best ranked team performed better than the lowest ranked team on WAnT, vertical jumps and the Bosco test. Stepwise discriminant analysis showed that stature and mean power during the Bosco test were the most important characteristics in TH players, accounting for 54.6% of the variance in team ranking. These findings indicate the contribution of particular physical fitness components (stature, fat free mass and anaerobic power) to excellence in TH. In addition, the use of the Bosco test as an assessment tool in talent identification and physical fitness monitoring in this sport is further recommended.

Effects of Load and Contraction Velocity During Three-Week Biceps Curls Training on Isometric and Isokinetic Performance

Ingebrigtsen, J, Holtermann, A, and Roeleveld, K. Effects of load and contraction velocity during three-week biceps curls training on isometric and isokinetic performance. J Strength Cond Res 23(6): 1670-1676, 2009-The velocity-specificity principle in training is well established by studies applying isokinetic training devices. However, the contraction velocity during customary resistance training using barbells is rarely stable and can be manipulated in several ways. By manipulating load and intention of movement, the significance of contraction velocity during barbell training on gains in strength-related parameters was investigated. Twenty-seven subjects (divided into 3 experimental groups) performed standardized biceps curls 3 times a week for 3 weeks under the following conditions: high load and slow contraction velocity (HS), high load and fast contraction velocity (HF), and low load with fast contraction velocity (LF). Twelve subjects received no intervention, serving as controls (C). Elbow flexion strength was tested before and after the training period at both isometric and 4 isokinetic contraction velocities (30, 90, 240 and 300°/sec) using a dynamometer. Rate of force development (RFD) was calculated in 100 millisecond epochs from isometric torque curves. Increased maximal isometric strength was seen in HF (9.7%), whereas HS improved slow isokinetic strength (8.5%). There were no improvements in force performance for LF and C. In none of the groups were changes in RFD observed. These findings support the principle of training specificity, highlighting the importance of details concerning contraction velocity on the outcome of resistance training using free weights.

Validation of a Commercial and Custom Made Accelerometer-Based Software for Step Count and Frequency during Walking and Running

Background: Walking and running are main human locomotor activities during daily living, and well known to strongly predict health impairment and mortality. Hence, the main aim of this study was to assess the ability of a commercial and a custom made software for determining number of steps and step frequency during walking and running with an accelerometer in a semi-standardized setting. Methods: 20 subjects (6 males and 14 females) equipped with the Actigraph GT3X+ tri-axial accelerometer at the thigh and the hip carried out a protocol of three walking speeds and three running speeds. The validity of the accelerometer ability to count steps and estimate step frequency was determined by comparing data from ActiLife 5 and custom made software (Acti4) with observations from video recordings from the different activity speeds. Results: No significant differences in number of steps or step frequencies were found between the video observations and Acti4 measures in any walking and running speeds. The ActiLife 5 software recorded a significantly lower number of steps and step frequencies compared to the video observations in the three walking speeds and in the fastest running speed. Pearson’s correlations and Bland-Altman plots indicated large to very large correlations and a high degree of agreement between the video observations and both the custom made Acti4 software and commercially available ActiLife software at all speeds of walking and running. Conclusion: The custom made Acti4 software showed valid for estimating steps and step frequency at slow, moderate and fast speeds of walking and running. Combined with the ability to detect activity type, the Acti4 software provides a valid objective method for measurements of number of steps and step frequencies.