Cycling is one of the most widely practiced physical activities, both as a means of transportation and as a competitive and recreational sport. Although riders are continuously exposed to mechanical vibration originating from the interaction between the rider, the bicycle and the riding surface, no comprehensive synthesis of the existing evidence of the effects of vibration on the different types of human responses is available to date. After systematically reviewing the literature available to date on the effects of vibration exposure on human responses, the results showed that the exposure limits imposed by the European Directive 2002/44/EC are easily reached in cycling for vibration transmitted to the hands and to the lower back. Additionally, the body parts in contact with the bike have been observed to be the most exposed. Contrary to hands and the lower back, vibration transmission to feet has not been specifically examined yet; therefore, a further understanding of foot-transmitted vibration (FTV) during cycling is essential. No specific standard has been developed for FTV, therefore the standard that regulates whole-body vibration (WBV) exposure (ISO 2631) has to be used. The experimental part of the work aimed to: evaluate vibration exposure at the foot, assess the suitability of ISO 2631 for the evaluation of FTV during cycling, and identify the main frequencies at which vibrations are transmitted to the feet, and how they change in the different phases of the pedalling cycle. The work consisted in measurements of vibrations at the foot and at the pedal during road and mountain bike rides in real-world conditions. The study involved three healthy female subjects, each of them performed two rides, one on a road bike and one on a mountain bike. Triaxial acceleration was measured at the pedal and at the foot using inertial measurement units (IMUs). Vibration exposure was evaluated following ISO 2631 guidelines; acceleration root-mean square (RMS) values, power-spectral density (PSD) functions, and transmissibility both for the overall pedalling cycle and for the different phases were calculated. The results showed that vibration levels measured at the foot were consistently higher than those measured at the pedal, indicating that the foot represents a crucial point for vibration exposure during cycling. The choice of the metric used in vibration exposure evaluation was found to be essential for a correct analysis: VDV (vibration dose value) more efficiently represented the energetic content of vibration, while A(8) values were influenced by direction-related multiplying factors. The application of ISO 2631 weighting curves resulted in a substantial reduction of the vibration energetic content, in particular for frequencies higher than 25 Hz. The peak in transmissibility was found to be at around 65 Hz; therefore, the application of the weighting curves seems to highly influence the evaluation of important vibration components. In addition, a comparison of the variations in peak transmissibility frequency and the distribution of muscle activation and power production across the different phases of the pedalling cycle, suggests an influence of muscle activation on vibration transmission. Overall, this study provides a preliminary in-field characterization of FTV during cycling, highlighting some limitations in the use of ISO 2631 for its assessment. The findings offer preliminary insights that may be useful for future studies aimed at better characterizing the effects of FTV on the rider and at reducing vibration transmission to the feet during cycling.
Il ciclismo è una delle attività più diffuse, sia come mezzo di trasporto sia come sport praticato a livello competitivo o amatoriale. Tuttavia, sebbene i ciclisti siano continuamente esposti a vibrazioni generate dall’interazione tra il corpo, la bicicletta e il suolo, ad oggi non è disponibile una sintesi completa degli effetti sul corpo umano delle vibrazioni trasmesse durante la pedalata. Una revisione sistematica della letteratura disponibile sugli effetti delle vibrazioni nel ciclismo ha mostrato che i limiti di esposizione imposti dalla Direttiva Europea 2002/44/EC vengono facilmente raggiunti per le vibrazioni trasmesse alle mani e alla regione lombare. Inoltre, le parti del corpo in diretto contatto con la bicicletta risultano essere le più esposte. A differenza delle mani e della zona lombare, la trasmissione delle vibrazioni ai piedi non è stata ancora oggetto di analisi specifiche; pertanto, una maggiore comprensione di questo fenomeno risulta essenziale. Attualmente non esiste uno standard specifico per la valutazione delle vibrazioni trasmesse ai piedi e, di conseguenza, viene applicato lo standard che regola la valutazione dell’esposizione alle vibrazioni al corpo intero (ISO 2631). La parte sperimentale di questo lavoro ha avuto come obiettivi la valutazione dell’esposizione alle vibrazioni a livello del piede, la verifica dell’idoneità dello standard ISO 2631 per la valutazione delle vibrazioni trasmesse ai piedi durante il ciclismo e l’individuazione delle principali frequenze alle quali le vibrazioni vengono trasmesse ai piedi, analizzando inoltre come tali frequenze varino nelle diverse fasi della pedalata. L’acquisizione delle accelerazioni al piede e al pedale è avvenuta durante uscite in bici da strada o mountain bike svolte in condizioni reali su strade e sentieri. Lo studio ha coinvolto tre soggetti sani, ciascuno dei quali ha effettuato due uscite in bicicletta, una su strada e una in mountain bike. Le accelerazioni triassiali sono state misurate a livello del piede e del pedale mediante unità di misura inerziali (IMU). L’esposizione alle vibrazioni è stata valutata seguendo le linee guida dello standard ISO 2631; le grandezze utilizzate per l’analisi sono state l’accelerazione RMS, le funzioni di densità spettrale di potenza (PSD) e la trasmissibilità delle vibrazioni sia nell’intero ciclo di pedalata sia nelle singole fasi. I risultati hanno evidenziato che i livelli di vibrazione misurati al piede sono superiori a quelli misurati al pedale, indicando che il piede rappresenta un punto particolarmente esposto alle vibrazioni durante il ciclismo. È emerso inoltre che la scelta delle metriche per la valutazione dell’esposizione è fondamentale per una corretta interpretazione dei risultati: il Vibration Dose Value (VDV) si è dimostrato più rappresentativo del contenuto energetico delle vibrazioni, mentre i valori di A(8) risultano fortemente influenzati da fattori moltiplicativi dipendenti dalla direzione delle vibrazioni. L’applicazione delle curve di ponderazione previste dallo standard ISO 2631 ha comportato una riduzione significativa del contenuto energetico delle vibrazioni, in particolare per frequenze superiori a 25 Hz. Il picco di trasmissibilità è stato individuato intorno ai 65 Hz, indicando che una componente rilevante delle vibrazioni risulta fortemente influenzata dall’applicazione delle curve di pesatura. Inoltre, il confronto tra le variazioni nella trasmissione delle vibrazioni e la distribuzione dell’attivazione muscolare e della produzione di potenza nelle diverse fasi della pedalata suggerisce un’influenza del livello di attivazione muscolare sulla trasmissione delle vibrazioni. Nel complesso, questo studio fornisce un’analisi preliminare della trasmissione delle vibrazioni al piede durante il ciclismo, mettendo in evidenza alcune limitazioni nell’utilizzo dello standard ISO 2631 per la loro valutazione. I risultati ottenuti rappresentano un punto di partenza per futuri studi finalizzati a una migliore comprensione degli effetti delle vibrazioni sul ciclista e allo sviluppo di soluzioni volte a ridurre la trasmissione delle vibrazioni ai piedi.
Foot-transmitted vibration in cycling: a preliminary study
Bianucci, Allegra
2024/2025
Abstract
Cycling is one of the most widely practiced physical activities, both as a means of transportation and as a competitive and recreational sport. Although riders are continuously exposed to mechanical vibration originating from the interaction between the rider, the bicycle and the riding surface, no comprehensive synthesis of the existing evidence of the effects of vibration on the different types of human responses is available to date. After systematically reviewing the literature available to date on the effects of vibration exposure on human responses, the results showed that the exposure limits imposed by the European Directive 2002/44/EC are easily reached in cycling for vibration transmitted to the hands and to the lower back. Additionally, the body parts in contact with the bike have been observed to be the most exposed. Contrary to hands and the lower back, vibration transmission to feet has not been specifically examined yet; therefore, a further understanding of foot-transmitted vibration (FTV) during cycling is essential. No specific standard has been developed for FTV, therefore the standard that regulates whole-body vibration (WBV) exposure (ISO 2631) has to be used. The experimental part of the work aimed to: evaluate vibration exposure at the foot, assess the suitability of ISO 2631 for the evaluation of FTV during cycling, and identify the main frequencies at which vibrations are transmitted to the feet, and how they change in the different phases of the pedalling cycle. The work consisted in measurements of vibrations at the foot and at the pedal during road and mountain bike rides in real-world conditions. The study involved three healthy female subjects, each of them performed two rides, one on a road bike and one on a mountain bike. Triaxial acceleration was measured at the pedal and at the foot using inertial measurement units (IMUs). Vibration exposure was evaluated following ISO 2631 guidelines; acceleration root-mean square (RMS) values, power-spectral density (PSD) functions, and transmissibility both for the overall pedalling cycle and for the different phases were calculated. The results showed that vibration levels measured at the foot were consistently higher than those measured at the pedal, indicating that the foot represents a crucial point for vibration exposure during cycling. The choice of the metric used in vibration exposure evaluation was found to be essential for a correct analysis: VDV (vibration dose value) more efficiently represented the energetic content of vibration, while A(8) values were influenced by direction-related multiplying factors. The application of ISO 2631 weighting curves resulted in a substantial reduction of the vibration energetic content, in particular for frequencies higher than 25 Hz. The peak in transmissibility was found to be at around 65 Hz; therefore, the application of the weighting curves seems to highly influence the evaluation of important vibration components. In addition, a comparison of the variations in peak transmissibility frequency and the distribution of muscle activation and power production across the different phases of the pedalling cycle, suggests an influence of muscle activation on vibration transmission. Overall, this study provides a preliminary in-field characterization of FTV during cycling, highlighting some limitations in the use of ISO 2631 for its assessment. The findings offer preliminary insights that may be useful for future studies aimed at better characterizing the effects of FTV on the rider and at reducing vibration transmission to the feet during cycling.| File | Dimensione | Formato | |
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2026_03_Bianucci.pdf
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2026_03_Bianucci_Executive Summary.pdf
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https://hdl.handle.net/10589/250558